基坑监测系统(外文文献) (5)

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软土地层地铁深基坑施工智能化监测技术研究

应力重新排列，就有可能出现变形。

这种变形一旦超出正常范围，就会严重威胁到主要结构及基坑的稳固，甚至可能威胁到附近的建筑、地下管线的安全。

针对这类问题，常规的解决方案是采用监测设备对施工过程进行实时监测，即时获取周边环境的真实情况，并立即发出预警，防止风险的产生，从而确保施工的安全、经济、稳定及建设的顺利进行。

1 深基坑智能监测的必要性鉴于地铁深基坑的挖掘深度很大，加上支护困难，且其附近的环境复杂，因此经常会存在许多潜在的危险。

通常，基坑事故可能涉及支护结构的破裂、土体结构的受损，还有因为基坑的挖掘而对附近环境造成伤害。

经过调查研究，基坑事故的发生，其中7%~8%源自勘察失误，而40%的原因则归咎于设计上的缺陷。

此外，施工过程中的问题占比大约为40%。

业主和监督人员的管理疏漏、缺乏有效的监测，以及对水资源的认知程度的缺乏，这些多元化的原因占比12%~13%。

尽管因为监测的直接影响所引发的事故占比不多，但通常的基坑事故往往会产生相互关联，因此，对其进行即时的监测和预警，将是在设计和施工出现疏漏之后，最终的安全防护保障。

对比人工监测，智能监测的优点主要表现在运行效率高、连贯性好、监测的时长跨度大，还有即时的预警信息。

通过使用智能监测整合系统，可明显降低监测者的重复操作，并降低因为人工疏忽导致的监测延后或错误发生的概率。

在软土地层稳定性不高的情况下，深基坑一体化智能监测系统的构建与使用显得尤为重要[1]。

摘要为了确保地铁深基坑的施工安全，需通过监测手段实时掌握周围地层、支护系统、管道、水位及建筑物的状况。

而在软土地层地铁深基坑所处的复杂且危险的环境中，由于人工监测的延迟，可能会导致意外事故的发生。

研究结果表明，通过采用智能化的监测手段，可以在软土地层深基坑项目中，显著提高监测预警的效率，极大地填补人工监测“滞后反应”的不足，从而有力地预防工程损害和环保问题的出现。

关键词深基坑；智能化；监测；软土地层；研究中图分类号 TU753 文献标识码 ADOI 10.19892/ki.csjz.2024.06.51Abstract In order to ensure the construction safety of subway deep foundation pit, it is necessary to grasp the situation of the surrounding strata, supporting system, pipeline, water level and building in real time by monitoring means. In the complex and dangerous environment of deep foundation pit in soft soil layer, the delay of manual monitoring may lead to accidents. The research results show that by adopting intelligent monitoring means, the efficiency of monitoring and early warning can be significantly improved in the deep foundation pit project of soft soil layer, and the deficiency of “delayed response” of manual monitoring can be greatly filled, so as to effectively prevent the occurrence of engineering damage and environmental protection problems.Key words deep foundation pit; intelligent; monitor; soft soil layer; study伴随着城市规模化的快速发展，城市的交通负担日益沉重，尽管轨道交通能够有效减轻地面的交通负担，然而在地铁站的软土地层深基坑的建造阶段，仍然有许多潜在的风险。

基坑监测系统(外文文献) (10)

GEOPHYSICS,VOL.66,NO.1(JANUARY-FEBRUARY 2001);P .78–89,9FIGS.Case HistoryThe use of geophysical prospecting for imaging active faults in the Roer Graben,BelgiumDonat Demanet ∗,Fran¸c ois Renardy ∗,Kris Vanneste ∗∗,Denis Jongmans ‡,Thierry Camelbeeck ∗∗,and Mustapha Meghraoui §ABSTRACTAs part of a paleoseismological investigation along the Bree fault scarp (western border of the Roer Graben),various geophysical methods [electrical proﬁling,elec-tromagnetic (EM)proﬁling,refraction seismic tests,elec-trical tomography,ground-penetrating radar (GPR),and high-resolution reﬂection seismic proﬁles]were used to locate and image an active fault zone in a depth range between a few decimeters to a few tens of meters.These geophysical investigations,in parallel with geomorpho-logical and geological analyses,helped in the decision to locate trench excavations exposing the fault surfaces.The results could then be checked with the observations in four trenches excavated across the scarp.Geophysical methods pointed out anomalies at all sites of the fault po-sition.The contrast of physical properties (electrical re-sistivity and permittivity,seismic velocity)observed be-tween the two fault blocks is a result of a difference inthe lithology of the juxtaposed soil layers and of a change in the water table depth across the fault.Extremely fast techniques like electrical and EM proﬁling or seismic refraction proﬁles localized the fault position within an accuracy of a few meters.In a second step,more detailed methods (electrical tomography and GPR)more pre-cisely imaged the fault zone and revealed some struc-tures that were observed in the trenches.Finally,one high-resolution reﬂection seismic proﬁle imaged the dis-placement of the fault at depths as large as 120m and ﬁlled the gap between classical seismic reﬂection proﬁles and the shallow geophysical techniques.Like all geo-physical surveys,the quality of the data is strongly de-pendent on the geologic environment and on the contrast of the physical properties between the juxtaposed for-mations.The combined use of various geophysical tech-niques is thus recommended for fault mapping,particu-larly for a preliminary investigation when the geological context is poorly deﬁned.INTRODUCTIONThis paper describes the application of various geophysical prospecting techniques to locate and image Quaternary fault zones as part of a paleoseismological project (Meghraoui et al.,2000).Paleoseismology aims to determine the Late Pleistocene and Holocene history of near-surface faulting often associated with large earthquakes.This usually requires the excavation of shallow trenches across the trace of the suspected active fault.Active normal faults exposed at the surface are usuallyPublished on Geophysics Online July 11,2000.Manuscript received by the Editor March 22,1999;revised manuscript received June 15,2000.∗Liege University,LGIH,Bat B19,4000Liege,Belgium.E-mail:ddemanet@ulg.ac.be.‡Formerly Liege University,LGIH,Bat B19,4000Liege,Belgium.Presently LIRIGM,Universite Joseph Fourier-Grenoble 1,BP 53,F 38041Grenoble Cedex 9,France.E-mail:djongmans@ulg.ac.be.∗∗Royal Observatory of Brussels,av.Circulaire 3,1180Brussels,Belgium.§CNR-CS,Geologia Tecnica,via Eudossiana 18,00184Rome,Italy.c 2001Society of Exploration Geophysicists.All rights reserved.expressed in the topography as fault escarpments.However,in intraplate areas characterized by relatively low rates of tec-tonic deformation,the geomorphic expression of an active fault may be very subtle as a result of the complex interplay among tectonic,depositional,and erosional processes or intensive agricultural exploitation.However,nondestructive geophysi-cal prospecting techniques may be applied to map the near-surface fault trace with great accuracy.In the last few years,a large number of high-resolution seismic reﬂection surveys have been conducted (e.g.,Williams et al.,1995;Palmer et al.,1997;78Imaging Active Faults79Van Arsdale et al.,1998)to provide information on Quater-nary fault geometry and timing.For very shallow investigation, ground-penetrating radar(GPR),which can bridge the gap be-tween high-resolution seismic surveys and trenching,has been applied by Cai et al.(1996)in the San Francisco Bay region. At the border of Nevada and California,Shields et al.(1998) have used several geophysical techniques(seismic reﬂection, magnetics,and electromagnetics)to locate the extension of the Parhump Valley fault zone.This paper presents the results of a geophysical campaign performed in the Bree area(Roer Graben,northeast Belgium)as a reconnaissance tool prior to trenching,which included refraction seismic records,electro-magnetic(EM)and electrical proﬁling,electrical tomography, ground penetrating radar(GPR),and high-resolution seismic reﬂection proﬁles.The foremost aim of this investigation was to determine the exact position of an active fault to precisely locate a subsequent trench.A second objective was to image the fault zone at shallow depths,therby allowing a direct com-parison with trench data and hence a conﬁdent extrapolation of direct observations to greater depths.GEOLOGICAL SETTING AND TECTONIC ACTIVITY The Roer Graben,which crosses three countries(Belgium, The Netherlands,and Germany),is bounded by two north–northwest,south–southeast-trending Quaternary normal fault systems(Figure1).The eastern boundary is deﬁned by the Peel boundary fault,where the5.4-M W1992Roermond earthquake occurred(Camelbeeck and van Eck,1994);while the western boundary is deﬁned by the Feldbiss fault zone,which is partially located in Belgium.Evidence of tectonic activity in the Roer Graben is given by(1)the strong subsidence during the last 150000years(Geluk et al.,1994),(2)the Quaternary faults and their associated morphology along theﬂanks of the graben, (3)the0.8–2-mm/yr vertical rate of deformation obtained by the comparison of levelings during the last100years(Van den Berg et al.,1994;M¨alzer et al.,1983),and(4)the present-day seismic activity(Camelbeeck and van Eck,1994).For the Feldbiss fault zone,tectonic activity is mainly indi-cated at depth by seismic proﬁles that show more than600m of offset in Neogene deposits(Demyttenaere and Laga,1988)and about150m at the base of the Pliocene(De Batist and Versteeg, 1999).By considering the offset of the main terrace of the Mass River determined by Paulissen et al.(1985),Camelbeeck and Meghraoui(1998)obtain0.08±0.04mm/year for the average Late Pleistocene vertical deformation along the Feldbiss fault. Near the town of Bree(Figures1and2)and along the Feldbiss fault,a prominent northwest–southeast-trending fault scarp separates the Campine plateau to the west from the Roer Valley Graben to the east(Paulissen,1973).The geomorphic expression of the scarp consists of a10-km-long escarpment that has15–20m of vertical topographic relief(Figure2).The Belgian Geological Survey acquired150reﬂection seismic lines in the region with a dozen crossing the scarp(Demyttenaere, 1989).On different sections,the scarp coincides at the surface with the surface projection of the Feldbiss fault zone and can therefore be considered the morphological expression of the fault’s recent activity.The Bree fault scarp corresponds to the northeastern border of the Campine Plateau(Figure2),which is covered by terrace gravels deposited by the Mass River(Zutendaal gravels)during the Cromerian(between770000and350000years BP)and which overly sands of Upper Miocene age(Diest Formation)(Paulissen et al.,1985).In the downthrown block (Roer Graben),the Zutendaal gravels have been eroded by the Rhine and Maas Rivers,which afterward deposited the Bocholt sands(Paulissen,1983).These formations constitute the basement on which the Maas formed its different terraces at the end of the Middle Pleistocene and during the Late Pleistocene.These terraces are the typical landscape of the region.The region was later covered with aeolian sands during the Saalian and Weichselian glacial ages,which were mixed with the other near-slope deposits in the vicinity of the fault scarp.Aﬁnal phase of deposition created the Holocene alluvium in the center of the Maas Valley.The lithology logs of two boreholes(Van der Sluys,1997)drilled on each side of the scarp are given in Figure3.On the Campine plateau(hole H1),the Zutendaal gravels directly overlie the Upper Miocene sands of the Diest Formation,which were encountered at 11m depth.In the Roer Graben(hole H2),the thickness of the Middle Pleistocene river terraces reaches40m,while the top of the Diest Formation was found at233m depth,belowF IG.1.Quaternary faults and seismic activity in the lower Rhine embayment.The Bree fault scarp is located along the Feldbiss fault southeast of the town of Bree.80Demanet et al.a succession of sand and clay layers from Lower Pliocene to Upper Pliocene.The depth difference in stratigraphic horizons between the two boreholes gives strong evidence of tectonic activity along the Feldbiss fault zone.Multiple scarplets are superposed on the overall fault scarp,and the frontal fault trace consists of an en echelon geom-etry that suggests a component of left-lateral slip.The fault dips 70◦northeast and offsets young deposits (mainly late Weichselian aeolian cover sands and local alluvial terraces).Leveling proﬁles across the frontal fault scarp yield a vertical displacement ranging from 0.5to 3m.A three-year detailed paleoseismic investigation (1996–1998)shows that this frontal scarp corresponds to the latest coseismic (occurring during an earthquake)surface ruptures along this segment of the Feld-biss fault.These studies (Camelbeeck and Meghraoui,1996,1998)suggest that the most recent large earthquake occurred along the fault scarp between 610and 890A.D.and produced a vertical coseismic displacement of 0.5to 1.0m,with a mini-mum moment magnitude estimated as 6.3M W .Paleoseismic in-formation combining the trench and geomorphic observations suggests the occurrence of two surface-faulting earthquakes during the last 20000years.A third dates between 28000and 42000years BP .DATA ACQUISITIONFigure 2shows the location of the four sites where geophysical proﬁles were performed perpendicular to the fault strike.At these sites trenches were later excavated for a paleo-seismic study (Meghraoui et al.,2000).Six geophysical methods were applied across the scarp:(1)electrical proﬁling,(2)EM proﬁling,(3)electrical tomography,(4)GPR,(5)seismicF IG .2.Location and geological map showing the frontal escarpment of the Feldbiss fault near Bree and the studied sites (labeled 1to 4).The seismic line (SL)is located between sites 1and 2,at a right angle to the scarp.H1and H2are the boreholes described in Figure 3.Contours indicatetopography.F IG .3.Stratigraphic logs of boreholes H1and H2along a schematic southwest–northeast cross-section (after Van der Sluys,1997).Imaging Active Faults81refraction tests,and(6)high-resolution seismic reﬂection pro-ﬁles(Telford et al.,1990;Reynolds,1997).Geophysical tests were performed along the axis of each planned trench except for the seismic reﬂection proﬁle,which was carried out between sites1and2(Figure2).As aﬁrst step,the variation of the ap-parent ground resistivity along the scarp was measured with electrical and/or EM proﬁling.EM surveying was conducted with two separate coils connected by a reference cable moved along the proﬁle at discrete intervals with a constant coil spac-ing(Reynolds,1997).The instrument provides a direct reading of the apparent resistivity of the ground.In this study,the mea-surement spacing was5m and the intercoil separation was 10m.With horizontal coils,the maximum contribution to the secondary magneticﬁeld theoretically arises from a depth of around4m.In electrical proﬁling,a Schlumberger conﬁguration with cur-rent electrodes spaced12m apart(50m for site4)was moved perpendicular to the proﬁle,providing measurements of the apparent resistivity of the ground as a function of distance.An electrical tomography survey was performed using the Lund imaging system(Dahlin,1996)with a Wenner conﬁguration and an electrode spacing of1or2m.The data were processed with the algorithm proposed by Loke and Barker(1996)to ob-tain a resistivity section.According to the proﬁle length,the investigation depth was between5and15m.GPR proﬁles were also performed at three sites with a120-MHz transmitting an-tenna and at site3with a50-MHz antenna.A static correction was made with a mean velocity of80to90mm/ns determined from scattered events.The penetration depth strongly depends on the ground resistivity(ranging between50and500ohm-m in the Bree area)and was limited to a few meters.The GPR vertical resolution was smaller than0.5m with the120-MHz an-tenna used.At two sites,seismic refraction proﬁles,44and70m long,were carried out with a geophone spacing of1m and three toﬁve shots.The source was a hammer,and twenty-four10-Hz geophones were connected to a16-bit seismograph.Finally, one seismic reﬂection line was run in a northeast–southwest direction perpendicular to the fault scarp(Figure2).The pro-ﬁle extends150m with a4-m source interval.A gun provided the source,stackedﬁve times for each source location.The op-timum window(Hunter et al.,1984)was determined from30to 56m from a walkaway test.Data were recorded with a16-bit seismograph from40-Hz geophones.The stacked data have a maximum of six-fold subsurface coverage.Processing was performed using SU software(Cohen and Stockwell,1998), and the sequence included static corrections,F-Kﬁltering, NMO corrections,prestack band-passﬁltering,CDP stack and poststack band-passﬁltering.RESULTS AND INTERPRETATIONThe results of geophysical tests parallel to trenches T1to T4 are presented in Figure4and Figures6to8as well as a simpli-ﬁed geological description of each trench.The seismic reﬂec-tion proﬁle is shown in Figure5.Site1Theﬁrst site is located near a stream that cuts a small uplifted alluvial terrace.The trench,which is only2m deep,reveals late Weichselian cover sands,the upper part of which has been reworked by the small river(Figure4a).Disruption of(1)twogravel horizons within the cover sands and(2)the bleachedHolocene soil at the top indicates the near-surface presenceof a normal fault dipping to the northeast and closely aligningwith the frontal escarpment.An overlying soil bed just belowthe plough zone does not appear to be affected.Electrical proﬁling data clearly delineate the fault at a dis-tance between50and65m(Figure4a)by a sharp increase ofthe apparent resistivity values,from70ohm-m in the south-west block to more than250ohm-m in the northeast block(Figure4b).An accurate location(within a few meters)ofthe fault is,however,impossible to assess.The electrical to-mography section(Figure4c)shows a strong lateral resistivityvariation around50m with a contact dipping to the northeast.In the southwest block,a2-m-thick resistive layer overlies aconductive formation,while the northeast block consists onlyof the resistive layer.Here,the fault juxtaposing different soillayers can be located at the surface with an accuracy<2m.A second strong lateral resistivity variation at20m could beinterpreted as a fault dipping to the southwest.However,thiswas shown neither on the seismic proﬁle nor in the trench,andthe anomaly probably results from a sedimentary variation.A70-m-long seismic refraction proﬁle was performed acrossthe scarp.The time–distance graph inferred from the refractedwave analysis for the direct shot(Figure4b)shows an unusualdecrease of the apparent velocity from1690to720m/s in thesubsurface.This crossover point is located around50m andﬁts perfectly with the position of the fault.The interpretationof the seismic data(Figure4a)with the generalized recipro-cal method(Palmer,1981)shows that the conductive underly-ing layer is characterized by a relatively high seismic velocity(V p=1400m/s).In the southwest part of the section,this hori-zon is covered by a thin layer with a velocity of470m/s,whichdramatically increases in depth across the fault to reach4m inthe hanging wall.The limit between the two seismic horizonscould correspond to the depth of the water table,which wasless than2m in the footwall.Both geophysical methods clearlyindicate the presence of a fault below the topographic scarp,juxtaposing two blocks with different resistivity and seismicvelocity values.The corresponding GPR section is presentedin Figure4d,where theﬁrst30ns corresponding to the directwave have been muted.The maximum penetration depth isabout4m,corresponding to a two-way traveltime of100ns.In the southwest part,the section reveals two main horizontalreﬂectors(R1and R2),which are clearlyﬂexured and cut bytwo fault branches.The main one(F1)is located at about50malong the proﬁle,whereas the second fault branch F2prob-ably does not extend to within the reach of the trench.Theshallower reﬂector(R1)is located at1.6m depth(40ns)andcorrelates with the lower gravel horizon exposed at the bottomof trench1.The northeast part of the section is characterized bya wedge shape with a southwest-dipping strong reﬂector(R3)at its base.The base of the wedge is located at3.2m depth.Thedifferent layers inside the wedge appear to beﬂexured in thevicinity of the fault.Seismic line SL(Figure5),150m long,trends southwest–northeast and crosses the frontal escarpment(F)at a rightangle.In the Roer graben(northeastern block),the seismicsection reveals several well-deﬁned reﬂections down to0.2s.These seismic horizons are cut at105m by a fault(F)whose82Demanet et al.F IG.4.Site1.(a)Schematic stratigraphic cross-section and seismic velocity model.(b)Electrical proﬁling(EP)and seismictraveltime curves(SP).(c)Electrical tomography.(d)Radar section(120MHz).Imaging Active Faults 83location aligns well with the one delineated near the surface by the trench and shallow geophysical data.Displacement on this fault can be traced down to 150m.In the southwestern block,the penetration depth is lower and the reﬂections are less coherent.The bending and the disturbance of these reﬂec-tors,however,suggest the presence of two other faults at 45and 58m along the proﬁle (Figure 5).In the Roer Graben,the borehole data (Figure 3)and the seismic stratigraphy study of De Batist and Versteeg (1999)allow us to correlate prominent reﬂections with stratigraphic unconformities.The three main seismic horizons are at 40,110,and 200ms,corresponding to depth values of 30,82.5,and 150m with a seismic velocity of 1500m/s (Figure 5).The two deeper reﬂectors could coincide with the interface between the Mol sands and the underlying Brunssum I clay layer and with the top of the Miocene (formation of Diest),respectively.The shallower seismic horizon (30m)could correspond to the bottom of the Middle Pleistocene terrace deposits,which was found at 37m in borehole H2.However,borehole H2is situated within the graben at a greater distance from the border fault.In the footwall,the Middle Pleistocene river terraces are only about 11m thick and directly overlie the Late Miocene Diest sands,precluding the existence of correlative seismic reﬂectors on both sides of the fault.Site 2The second site is located a few hundred meters away from site 1but on a much steeper portion of the Bree fault escarpment.The trench at this site (Figure 6a)was between 2.5and 3.5m deep and exposed Middle Pleistocene coarse gravel deposits with intercalated lenses of clayey sand on the upper portion of the slope.The stratigraphy of the lower slopeis F IG .5.Seismic proﬁle across the Bree scarp near site 1with the surface topography.totally different,consisting of ﬁner grained cover sands and re-worked cover sands of Late Pleistocene (mainly Weichselian)age.From bottom to top the following succession is observed:reworked gravelly cover sands;a 20-cm-thick bed of clayey sand;ﬁnely laminated cover sands;a complex unit of grav-elly and silty sand containing an irregular,discontinuous clay level at its base;a bleached unit of silty sand;and ﬁnally the plough zone.The laminated sands and the overlying unit ex-hibit channel-like thickness variations.The upper and lower slopes are separated by a zone of two normal surface faults,dipping to the northeast and associated with a complex se-ries of colluvial gravels,sands,and silts produced by fault scarp degradation following surface rupture (Meghraoui et al.,2000).The presence of the fault is clearly shown on all the geo-physical results.The resistivity values obtained by EM and electrical proﬁling (Figure 6b)exhibit a sharp increase at the approximate emplacement of the fault,from 80ohm-m to the southwest to more than 140ohm-m in the northeast block.The resistivity increase is slightly shifted with regard to the fault trace,probably as a result of the fault dip.The time–distance graph inferred from the refracted wave analysis (Figure 6b)and the velocity model (Figure 6a)show a similar evolution with a dramatic lateral variation of the apparent velocity values from 1840to 710m/s in the layers below the plough zone.These sediment property contrasts primarily reﬂect the difference of water table level on both sides of the fault,with the fault acting like a hydrological barrier.In the footwall,the shallow water table limited the trench to a depth of 2to 2.5m.In the hanging wall,groundwater was not encountered down to at least 4.5m.A farm well located near the top of the slope indicates that this situation persists.Thus,the saturated footwall sediments are characterized by lower resistivity and higher seismic velocity84Demanet et al.F IG.6.Site2.(a)Schematic trench cross-section and seismic velocity model.(b)Electrical proﬁling(EP),electromagnetic proﬁling(EM),and seismic traveltime curves(SP).(c)Electrical tomography.(d)Radar section(120MHz).Imaging Active Faults85values.A2-D image of the fault zone was obtained by the elec-trical tomography method.Data processing(Figure6c)clearly indicated the fault position by a lateral resistivity variation at a distance of around20m.The fault-controlled groundwater level in the hanging wall is clearly shown on the tomographic section by a resistivity decrease at depth,resulting from the presence of saturated sand.In the vicinity of the fault,the wa-ter table depth in the hanging wall is estimated to be around 6m.On the northeastern side,the electrical section presents a more complex pattern,with low-resistivity values close to the surface.This may be related to the presence of irregular clay patches at the base of the channel-like structures described above.The last technique used in this study is GPR.The radar sec-tion is presented in Figure6d.A static correction has been applied with a mean velocity of90mm/ns.In the southwestern part of the section(0–20m),a few irregular reﬂections clearly appear between20and80ns(0.9and3.6m deep).The strong gully-shaped reﬂector may well correspond to aﬂuvial chan-nel within the Zutendaal gravels,below the reach of the trench. Around20m,the reﬂections are dipping northeastward toward the fault zone,probably as a result of fault movementﬂexur-ing.At that distance,one can also observe a variation of the penetration depth between the northeastern and southwestern parts of the section.This location corresponds to the fault trace mapped in the trench,and the perturbations in the reﬂections ﬁt with the structures observed in the exposed coarse gravel layers.In the northeast,the radar data show a succession of domes and troughs whose positions correspond to the series of channel-like features in the laminated cover sands and in the overlying unit.Apparently,these features do not correspond to realﬂuvial channels,but they are interpreted asﬂow folds in-duced by liquefaction and subsequent failure of the laminated sand unit,which may have been triggered by a paleoearthquake (Vanneste et al.,1999).Site3Site3is located about1.5km southeast of site1on theﬂank of a small river valley crossing the scarp.The frontal escarpment runs along the top of the hill,and the southwest–northeast-trending excavation has pointed out two major branches of normal faulting extending to just below the plough zone in the southwestern part(between65and72m)and a buried fault at about105m in the northeastern section(Figure7a).The west-ern fault zone exhibits major displacement,as it juxtaposes Middle Pleistocene(Zutendaal gravels)to Late Pleistocene sandy deposit;the eastern buried fault displaces these latter sediments only about1m(Meghraoui et al.,2000).EM pro-ﬁling(Figure7b)estimated the approximate location of the fault zone by an increase of apparent resistivity values from the southwest block(about95ohm-m)to the northeast block (125ohm-m).This fault zone was better delineated by the elec-trical tomography(Figure7c)between70and75m along the proﬁle.Contrary to site1,the dip of the fault was not clearly de-termined from the electrical section,which mainly shows a low-resistivity zone dipping to the southwest.The buried fault does not appear clearly on the tomography section and on the EM proﬁle,suggesting that its throw is not very important at shallow depth.A GPR proﬁle was performed50m to the southeast of the trench to avoid diffracted events generated by the presence of trees.In this area,the maximum penetration depth is about 6m,with an antenna of50MHz.The southwest fault zone is clearly shown by the fault-related structures and the termina-tion of reﬂectors,while the buried fault is again poorly indica-ted.On the other hand,20m to the south of the main fault zone an additional fault branch appears which could be the second major branch of the fault zone observed in the adjacent trench. Site4Site4is located5km to the southeast of site1(Figure2).In this area,the frontal escarpment occupies the lower part of the slope.The3.5-m-deep trench with a stratigraphic cross-section is given in Figure8a.It exposed coarse,clayey and gravelly Maas River sediments corresponding to the Zutendaal grav-els in the footwall,juxtaposed by a narrow fault zone to more ﬁne-grained,partly reworked cover sands with some gravel horizons in the downthrown block.Two wedges of reworked Maas material are present in the hanging wall close to the fault, wedging out downslope,whereas the main Maas River terrace is probably downthrown beneath the trench bottom.The di-rectly observable fault displacement is,however,limited to about60cm,based on the offset of the base of the laminated cover sands in Figure8a.Electrical and EM proﬁles(Figure8b)performed with dif-ferent spacing values,and hence different penetration depths, show a general decrease of resistivity across the fault zone with-out a strong gradient displaying the fault location.Below a shallow and irregular resistive layer,the upper7m on the elec-trical tomography section(Figure8c)are mainly characterized by a relatively uniform resistivity ranging between100and 200ohm-m with a disturbance around60m.Somewhat deeper, the section shows a lateral resistivity gradient across the fault and an asymmetrical synclinal structure in the downthrown block.The depth of the groundwater table was at least6m in the footwall and more than9m in the hanging wall,as indicated by hand borings.On the radar proﬁle(Figure8d),which has a penetration depth of about4m,the position of the main fault zone is shown by a distinct change in reﬂectivity and penetration depth be-tween footwall and hanging walls:the footwall is characterized by discontinuous,incoherent reﬂectors and small penetration depth,most probably resulting from the high clay content of the strongly altered Maas deposits.Some isolated reﬂectors,e.g., the dipping segment between35and45m,may correspond to the gravel-rich base of erosional channels,several of which have been identiﬁed on the trench wall.The hanging wall,on the other hand,shows more regular reﬂectors extending over a larger depth interval.The stratiﬁcation of the hanging-wall sediments is mostly parallel to the surface slope.At the base of the hill slope,the strata show a counterslope tilt because of thrusting along several detachment planes.This deforma-tion structure clearly appears on the radar section as a set of disrupted reﬂectors with associated diffractions.The general hanging-wall structure of an asymmetrical synform appearing on both the radar and the electrical tomography proﬁles indi-cates that deeper hanging-wall layers are slightly dipping to-ward the main fault.This has been conﬁrmed by hand bor-ings extending5m below the trench bottom.In particular,the strong reﬂector in the lower part of the radar section can be correlated to a30-to40-cm-thick clay bed dipping from the far。

地基基础检测信息管理系统的介绍与应用于春辉

地基基础检测信息管理系统的介绍与应用于春辉发布时间：2023-08-04T02:44:48.940Z 来源：《工程建设标准化》2023年10期作者：于春辉[导读] 建立较为完善的地基基础检测信息管理系统，实现从检测业务受理到检测场地踏勘，从检测数据实时上传到分析检测数据、出具检测报告，再到报告归档、上传到监督部门，实现监测、监管系统、检测设备管理、财务管理的信息互通，不仅大大提高了工作效率，还提高了检测过程的监管力度，科学准确分析各种干扰因素，提高检测单位的监管水平。

佛山市南海区建筑工程质量检测站广东佛山 528200摘要：建立较为完善的地基基础检测信息管理系统，实现从检测业务受理到检测场地踏勘，从检测数据实时上传到分析检测数据、出具检测报告，再到报告归档、上传到监督部门，实现监测、监管系统、检测设备管理、财务管理的信息互通，不仅大大提高了工作效率，还提高了检测过程的监管力度，科学准确分析各种干扰因素，提高检测单位的监管水平。

关键词：地基基础检测信息管理系统工程监管The Introduction and Application of Foundation Detection Information Management SystemYu ChunhuiFoshan Nanhai District Construction Engineering Quality Inspection Station, Foshan, Guangdong, 528200Abstract:Establish a relatively complete ground-based testing information management system to realize the information interchange of monitoring, supervision system, testing equipment management and financial management from testing business acceptance to testing site reconnaissance, from real-time uploading of testing data to analysis of testing data and issuance of testing reports, to archiving of reports and uploading to supervision departments, which not only greatly improves work efficiency.Key words:foundationinspection,information management system, engineering supervision引言当前在很多地区，地基基础检测仍采用比较落后的技术手段，由此引起了很多亟待解决的问题。

基坑监测系统(外文文献) (9)

GEOPHYSICS,VOL.65,NO.1(JANUARY-FEBRUARY 2000);P .83–94,11FIGS.Electrical imaging of engineered hydraulic barriersWilliam Daily ∗and Abelardo L.Ramirez ∗ABSTRACTElectrical resistance tomography (ERT)was used to image the full-scale test emplacement of a thin-wall grout barrier installed by high-pressure jetting and a thick-wall polymer barrier installed by low-pressure permeation in-jection.Both case studies compared images of electrical resistivity before and after barrier installation.Barrier materials were imaged as anomalies which were more electrically conducting than the native sandy soils at the test sites.Although the spatial resolution of the ERT was insufﬁcient to resolve ﬂaws smaller than a reconstruction voxel (50cm on a side),the images did show the spatial extent of the barrier materials and therefore the general shape of the structures.To verify barrier performance,ERT was also used to monitor a ﬂood test of a thin-wall grout barrier.Electrical resistivity changes were imaged as a saltwater tracer moved through the barrier at loca-tions which were later found to be defects in a wall or the joining of two walls.INTRODUCTIONThe cost for remediation of contaminated soil and ground-water at U.S.Department of Defense facilities has been esti-mated to exceed $200billion.Because more than 10000in-dividual sites are involved,each presenting a unique technical complexity,the entire task has become overwhelming.To mar-shal the resources of technology for the task,the ern-ment has attempted to develop new and innovative technolo-gies to reduce clean-up costs while protecting human health.One such technology is subsurface hydraulic barriers,which could be used to completely contain or slow the spread of a con-taminant.A successful barrier might contain the contaminant until natural degradation ran its course,conﬁne the contami-nant during some active remediation,or simply buy time for a site owner.However,for a barrier to succeed it must be easily constructed and cost effective as well as meet certain techni-cal performance criteria.To this end the U.S.Department of Energy has initiated a series of ﬁeld tests for different barrierManuscript received by the Editor June 22,1998;revised manuscript received January 18,1999.∗Lawrence Livermore National Laboratory,MS L-130,Livermore,California 94550.E-mail:daily1@;ramirez3@.c 2000Society of Exploration Geophysicists.All rights reserved.types at selected but geologically realistic sites.An important element of this program is to determine what methods might be useful to monitor the emplacement and verify the perfor-mance of these barriers without compromising their integrity (i.e.,nondestructively).The most general performance goal for a barrier is to stop or modify in some desired way the movement of a contaminant plume.This means that the emplaced material must modify the in-situ hydraulic conductivity and be continuous (free of holes).In addition,a man-made barrier may be required to meet other criteria,e.g.,seal to a natural barrier such as an aquitard.Evaluating performance can be difﬁcult.A key performance goal is to place the barrier materials in the desired conﬁgura-tion.For example,it may be very important to know the path-way and fate of emplaced barrier materials so that the barrier shape,location,and continuity are known.This type of infor-mation could be particularly useful if available in real time to guide construction or suggest any corrective action that might be required before a contractor leaves a site.An ideal technique for monitoring the emplacement and ver-ifying the performance of a barrier requires measurements only from the surface.It would provide a real-time,3-D image of the barrier with resolution capable of detecting even the small-est of defects.Until this ideal is realized,less-than-ideal but currently available technologies have been evaluated:cross-hole radar,electrical resistance tomography (ERT),borehole induction logging,and gaseous tracers.This paper reports the test results from one of these technologies:ERT.ELECTRICAL RESISTANCE TOMOGRAPHYERT is a technique for imaging the subsurface electrical structure using conduction currents.ERT was proposed inde-pendently twenty years ago by Henderson and Webster (1978)as a medical imaging modality and by Lytle and Dines (1978)as a geophysical imaging tool.Early development in geophysics was conﬁned to imaging rock core samples in the laboratory (Daily et al.,1987),but prototype data collection hardware and research-grade in-verse codes suitable for ﬁeld-scale applications soon followed (Ramirez et al.,1993).More recently,ERT has been developed8384Daily and Ramirezto detect leaks from large storage tanks(Ramirez et al.,1996), to monitor underground air sparging(LaBrecque et al.,1996b), and to map movement of contaminant plumes(Daily et al., 1998).During this entire period,data acquisition hardware and inversion algorithms have been improving rapidly to han-dle the new challenges.Useful evaluation of a subsurface barrier requires more than a series of selected2-D slices;rather,it requires a full3-D rendering of the structure.More recently,fully3-D algorithms have become available.One purpose of this demonstration is to test one of these inversion codes(LaBrecque et al.,1999) under realisticﬁeld conditions.The ERT algorithm we used is based on an Occams-type in-version that yields a minimum roughness solution consistent with the data and their errors.The2-D algorithm,based on a ﬁnite-element forward solver,is described by LaBrecque et al. (1996a).Also discussed are mesh requirements used for both the2-D and3-D algorithms.A simple generalization of this ap-proach to three dimensions is impractical,being computation-ally inefﬁcient.However,LaBrecque et al.(1998),describe a method for streamlining the forward solver using an iterative ﬁnite-difference formulation which makes3-D inversion prac-tical.Convergence for both algorithms is deﬁned when the rms error,normalized by the weights,is equal to the number of data points.BACKGROUNDTwo different types of barriers were studied using ERT.We ﬁrst discuss a thin diaphragm wall emplaced by high-pressure jetting of cementatious grout.This barrier was demonstrated at the Groundwater Remediation Field Laboratory located at Dover Air Force Base in Dover,Delaware.The second type was a thick wall emplaced by low-pressure injection of a vis-cous liquid of colloidal silica.This barrier was demonstrated at Brookhaven National Laboratory,Long Island,New York. Both were full-scale demonstrations conducted at clean(un-contaminated)sites.The strategy is to image the subsurface before and after the barrier emplacement so that,by comparing the two images,it is possible to remove the native heterogeneity and highlight only the disturbance from emplaced materials.As it turned out, both sites were quite resistive and the materials for both barri-ers relatively conductive.The resulting high-contrast conduct-ing anomalies were,for the most part,good electrical targets for imaging.In fact,the viscous liquid barrier was so electrically conducting that it could be imaged without the need to remove native heterogeneity in the electrical resistivity structure. Another test involvedﬂooding a hydraulically enclosed box formed by barrier walls.The strategy was to image the struc-ture before and after the chamber wasﬁlled with water and to compare the images.From such a comparison,it is possible to remove the barrier itself from the image,leaving only the disturbance from the water tracer and thereby determining the hydraulic integrity of the structure.THIN DIAPHRAGM WALL BARRIERThe test site is underlain by sediments generally composed of medium toﬁne sands with gravelly sand,silt,and clay lenses. Discontinuous clay lenses are common,and there are occa-sional gravelly sand lenses.Underlying these sands is the20-to28-ft-thick Calvert Formation,which generally consists of gray,ﬁrm,dense marine clays with thin laminations of silt and ﬁne sand.Included in the Calvert Formation is the Frederica aquifer,approximately22to28m below ground surface.De-tails of this geology can be found in Pellerin(1997a). Borehole induction logs and core sample measurements showed that the electrical resistivity of the sands varied be-tween300and600ohm-m while that of the clay was less than 50ohm-m.Resistivity of the grout varied widely,depending on the exact formulation and the curing boratory mea-surements place the electrical conductivity for the formulation between10and30ohm-m(Pellerin,1997a).There is good electrical contrast between the grout and the native sands.On the other hand,contrast may be low with the clay-rich soils that form the bottom of the barrier.Vertical grout panels were placed into the sands in vari-ous conﬁgurations with the goal of constructing a hydrauli-cally closed container.Each panel was formed by a high-velocity grout stream jetted horizontally from a lance as it was slowly withdrawn from the subsurface.The high-velocityﬂuid, a grout–bentonite mix,eroded a cavity deep into the soil.The resulting panels were placed so they overlapped along their sides to seal together and so they penetrated the clay acquitard (Calvert Formation)along their bottoms.(The clay provided the bottom to the box.)The entire structure was to become a hydraulically sealed box.Results of the technique are shown in Figure1,which is an excavation of the end of a test box formed by three intersecting panels.Notice the columnar structure near the center of the end panel.This is a cast of the grout-ﬁlled injection hole.Theﬁgure illustrates the wall thickness and how panels overlap at the edges to ensure a hydraulic seal.The plan was to emplace two concentric cylindrical walls in the sands,keying them along the bottom into the clays.The plan was later changed,after the boreholes used for ERT were installed,so that only the interior wall was emplaced.Figure2 is a plan view of the site,including the ERT boreholes and how the grout panels were toﬁt together.Each of the ERT electrode arrays indicated in Figure2con-tained15electrodes evenly spaced between the surface and 15m depth.Electrodes were fastened onto the outside of a PVC casing,and the borehole was completed with a sand backﬁll. This arrangement made it possible to use the holes for other geophysical or hydraulicmeasurements.F IG.1.Excavation of a thin diaphragm wall test barrier at theDover test site.ERT of hydraulic barriers 85The reconstruction mesh contained 144000voxels although only 48000(each approximately a 1-m cube)deﬁned the image;the others were used to properly model the boundaries.A total of 6480transfer resistance measurements were used for the re-constructions (12960if reciprocal measurements are counted).The number of parameters to be determined (144000)is much larger than the number of linearly independent data (6480),so the problem appears grossly underdetermined.Fortunately,because a solution of minimum roughness is calculated,each voxel is not an independent unknown but depends on the val-ues of nearby voxels (see LaBracque et al.,1996a).Preemplacement and postemplacement data were collected on the 16hole pairs shown in Figure 2to densely sample the image volume within the borehole ring.On October 3,1997,a total of 12960transfer resistances were measured for the baseline,half of these being reciprocal measurements used to estimate data accuracy (LaBrecque et al.,1996a).About 10hours were required to collect the data.The barrier wall was then installed in November,and ERT surveys were repeated between December 3and 4.Thin diaphragm wall resultsFigure 3shows the 3-D ERT images of a thin diaphragm wall barrier at the Dover test site.Figures 3a and 3b are the baseline image block before installation.The sands above about 10.7m depth have a conductivity of 10−5to 10−6mS/m and comprise most of the block.Figure 3b shows only the clay basement (conductivity >10−5mS/m).The barrier panels are to be keyed into this surface.The goal is to achieve a hydraulic seal between the clay and the walls,so the reader will want to pay special atten-tion to this part of the ERT image.The panel walls were installed to approximate a cylinder 10.6m in diameter.Figure 3c is a voxel-by-voxel difference in conductivity between the baseline and data collected on December 4,1997.The image is rendered transparentwhereF IG .2.Plan view of the thin diaphragm wall panel arrange-ment to create a large,hydraulically enclosed box,the bottom of which is a clay-rich aquitard at 10.5m depth.There are nine ERT electrode arrays (and twelve holes used for other geo-physics),each with ﬁfteen electrodes evenly spaced between 1and 15m depth.The dashed lines indicate the hole pairs used to acquire ERT data for the 3-D reconstruction block,which is 21.3m square and 14m deep.the conductivity change is <3×10−6mS/m.This threshold is arbitrary.A very much lower value produced several anoma-lies that we judged as measurement errors propagating through the algorithm.A very much higher value can make the barrier anomaly become arbitrarily thin.We believe this threshold value best represents the experimentally signiﬁcant changes in the subsurface.Because several things changed the subsurface conductivity during this period,other anomalies obscured the clear view of the barrier.These anomalies are discussed later.However,if we temporarily remove these features,the barrier becomes clear (Figure 3d).A quadrant of the barrier anomaly is re-moved to show features inside more clearly.From this last part it appears that the barrier structure is approximately as planned:a continuous cylinder extending from the clay–sand boundary to near the surface.Notice also that the wall thickness appears to be about 1.5m near the center but tapers toward the top and bottom edges.The exaggerated wall thickness as well as the tapering are both likely an artifact of the way the inversion algorithm searches for a smoothest solution.While Figure 3provides a good perspective view of the grout emplacement,some of the signiﬁcant details are difﬁcult to see.Figure 4shows,in plan view,a series of horizontal sections through the image volume.From these sections it is easier to see details.Starting near the bottom at 13m depth (Figure 4a),we see the anomalies associated with each ERT borehole.(These anomalies were removed from Figure 3d.)Because the other geophysical wells do not show such anomalies,we believe these conductive anomalies result from small amounts of salt water poured down the annulus of each ERT well to lower the con-tact resistance at the electrodes because of the dry sand backﬁll.Apparently,the salt water—all of which was not retained in the sand column by capillarity—drained to the hole bottom and in time found its way into the formation.The disturbance was conﬁned to the bottom of each hole because only 8or 9liters of water were used for each electrode array.Above 10.5m depth (Figure 4b),these anomalies are nearly absent.The deepest evidence of the barrier in the image is shown in Figure 4b at 10.5m.A section near the middle of the image block at 7.5m is shown in Figure 4c.ERT does not show the barrier shallower than 3.7m (Figure 4d);however,between 10.5and 3.7m there is a continuous,circular anomaly repre-senting the barrier.Before discussing the shallow section at 0.76m in Figure 4e,we will consider details of Figures 4a–4d.Grout injection to form each panel was between 13m (Figure 4a)and the surface,yet the ERT image extends from 10.5to 3.7m depth.We are not certain why the barrier anomaly does not extend over the full range,but two possibilities have been considered.First,the sensitivity of the ERT algorithm is lower at both the top and bottom of the image block because there is less data coverage there relative to the center of the image block.It is possible that the thin wall cannot be resolved with this reduced sensitivity.A more likely explanation for the lack of sensitivity at the bottom is the presence of the boratory measure-ments of grout conductivity depended on exact formulation and curing time but ranged between 10and 40ohm-m (Pellerin,1997a).The Calvert Formation (the clay)is between 10and86Daily and Ramirez100ohm-m and may offer insufﬁcient electrical contrast for the grout.One or both of these facts may explain why the barrier was not imaged as deep or as shallow as expected.Notice that the image shows no gap or ﬂaw in the barrier anomaly where it intersects the clay at about 10.5m depth.We believe that the ERT data are consistent with continuous grout panels as deep as 13m but were not imaged that deep because of low electrical contrast with the clays.In the 7.5-m section the barrier is a smooth (Figure 4c),con-tinuous circular anomaly.Resolution is insufﬁcient to distin-guish individual panels.Also notice that the barrier image is 9m in diameter,while injection was 10.6m in diameter.We do not know the reason for this difference.Examination of sections shallower than 3m reveals a se-ries of conductive anomalies as shown in Figure 4e.(These F IG .3.A thin diaphragm wall barrier at the Dover test site shown in Figure 2.(a)The 3-D image block of electrical conductivity before barrier emplacement (the baseline).(b)The baseline 3-D image block,showing only the formation >10−5mS/m electrical conductivity.This is the clay aquitard at 10.5m which forms the bottom of the enclosed barrier.(c)A voxel-by-voxel difference between the baseline and postemplacement image block.Only changes in electrical conductivity from 3×10−6and 2×10−5mS/m are shown.(d)Same as (c)but with all borehole and surface anomalies removed.Only the barrier remains,with a quadrant removed to make the inside visible.were also removed from Figure 3d.)They roughly deﬁne the circumference of a 15.2-m-diameter circle centered on the site.Prior to barrier installation,an asphalt base (called a mud mat),15.2m in diameter,was installed to catch any grout spill at the surface during the high-pressure injection.These anomalies are likely the result of small quantities of grout that spilled off the edge of the mud mat and washed into the surface soils.Detecting these anomalies in a region of the image block of reduced sensitivity is evidence that we should have imaged the grout wall above 3.7m depth if it were present.We conclude from the results that ERT provided an image of the thin-wall grout barrier even though some details of the images do not match our expectations of the structure (e.g.,anomaly diameter slightly different from the circle deﬁning the injection locations).ERT of hydraulic barriers 87The image is consistent with a thin wall (i.e.,40cm,typical of other thin diaphragm walls that had been excavated)and is uniform from top to bottom.There is little evidence from this image of grout material being spread much beyond the intended wall conﬁguration.Spatial resolution in these images was about 1m;therefore,details in the wall structure are not visible.Small holes or gaps at the intersection of two walls may not be resolved.If we assume that grout,unsuccessfully injected into the clay,would end up in the more permeable sands,then the undistorted interface of the panel at the sand–clay boundary is consistent with panels successfully keyed into the clay acquitard.The upper and lower extremes of the panels are not imaged by ERT.The lower parts were likely not imaged because of the low electrical contrast with the clay-rich sands below about 10.5m.We do not know why the panels are not imaged above 3m.F IG .4.The same thin diaphragm wall barrier shown in Figure 3but in plan view,with the conductivity differences of the image block sectioned at various depths.(a)The horizontal section at 13m,which is 2.5m into the clay.This is the bottom of the injection interval for the panels.The conductive anomalies correspond to the ERT borehole locations.(b)The horizontal section at 10.5m,which is the lower boundary of the barrier image and the upper bound of the clay layer.(c)The section at 7.5m,the image block center,showing the conductive anomaly of the barrier and a superimposed circle of 10.6m,which is the injection circle.(d)The section at 3.7m,which is the upper bound of the barrier anomaly.(e)The section at 0.76m.A circle of 15.2m is superimposed to show the size of the mud mat.THIN DIAPHRAGM WALL BARRIERVERIFICATION—FLOOD TESTERT was used to image tests on another barrier formed with the high-pressure,thin-diaphragm-wall technique at the same Dover test site described in the previous study.The box has a bottom formed by the clay aquitard at about 3.8m depth with thin-wall grout sides and is open at the top.Salt water was used as an electrical tracer to determine the presence and location of any leakage ﬂow paths.Figure 5illustrates the conﬁguration for the walls of this box.After the barrier was installed,a series of ERT electrode ar-rays was installed,each of 7electrodes equally spaced between the surface and 6m yout of the arrays is shown in Figure 5.The reconstruction mesh consisted of 21600voxels.Only 1400of those are shown in the image volume;the rest are used to model the boundaries.A total of 1078transfer88Daily and Ramirezresistance measurements were used for the reconstructions (2156if reciprocal measurements are counted).On August18,1997,a total of2156baseline transfer resis-tances were measured from the14hole pairs shown in Figure5. Then on August19at1100hours,saltwater tracer was added to the box through a screened water monitoring well near the center of the box.Sodium chloride was added to the native groundwater,with conductivity of1.5×10−4S/cm to raise it to4.3×10−3S/cm.This water was released into the box at 7.6liters/min.Three-dimensional ERT data sets were taken during theﬂood on August19and again on August20after theﬂood ended.The goal was to observe the water tracer by comparing the baseline and subsequent images.Results of thin diaphragm wall boxﬂood testFigure6shows the changes in resistivity of the image block as a result ofﬁlling this small,nearly rectangular box.The box walls and clay base are absent from the image since they are in both the pre-and postﬂood data.We made the image block transparent except where the de-crease in resistivity was30%(early in theﬂood)or35%(later in theﬂood or after theﬂood).In each case,this isocontour was then sectioned at11equally spaced intervals between the surface and6m depth.This rendering allowed us to view all sides of the tracer plume at each snapshot in time:1130to 1346hours on August19after about456liters of tracerwaterF IG.5.Plan view of the thin diaphragm wall panel arrangement to create a small,hydraulically enclosed box,the bottom of which is a clay-rich aquitard at3.8m depth.There are eight ERT electrode arrays,each with electrodes evenly spaced from the surface to6m depth.The injection borehole was a screened water-monitoring well.was added;1418to1620hours on August19after about1824 liters was added;and0703to1046hours on August20,which was about17hours after theﬂood ended.This format gives a good overall view of the plume as it is forming inside the barrier.In theﬁrst image the plume extends directly below the release point,but only to a depth of about 4.2m.By day’s end on August19,the plume has grown verti-cally to almost6m depth and is also much wider.There is no evidence at this high inﬁltration rate of the barrierﬁlling from the bottom up like a bathtub.On August20,approximately 17hours after inﬁltration ended,the plume is spreading hor-izontally to the left in theﬁgure.To better see the implica-tion of this,Figure7plots each of the plume sections in plan view.Figure7shows each of the plume sections for the early to-mograph(1130to1346hours)from0.6to5.4m depth.The iso-surface is relatively compact and is centered on the inﬁltration point.The connection with the surface is missing because the inﬁltration well was not screened all the way to the surface.The plume extends only to4.2m depth.The clay aquitard,which starts between3.8and4.0m,is likely impeding the downward migration of the plume so that it is not imaged below4.2m. This view of the plume also shows an interesting hydraulic pathway difﬁcult to observe in situ:the plume below3.0m ap-pears nearly disconnected from the plume above1.8m.There is only a narrowﬂow path connecting the two,shown here by the small isocontour at2.4m.This feature probably results from natural and subtle heterogeneity in the sands.However, we will see that its effect disappears in later images.By the end of theﬂood,Figure8has the plume extending all the way to5.4m depth,and it has also grown laterally. These images are still consistent with the plume being com-pletely contained by the grout walls,even though the contours extend a little past the barrier outline.(The images are spa-tially smoothed,so the lateral extent is probably exaggerated.) The plume extends about1.6m into the clay aquitard,which starts at about3.8m.Figure9shows a different behavior.While the plume has not changed signiﬁcantly in the top or bottom sections,between2.4 and4.2m depth the contour extends signiﬁcantly beyond the left panel.Even at1.8m depth,the contour points suspiciously to where two panels join at the top-left corner in theﬁgure.We interpret this as a leak in the left wall or at the junction between the left and upper wall.The breach appears to be between1.8 and4.2m depth.This barrier was excavated after the test, and the walls were examined.The two panels did not join completely in the upper-left corner at a depth of about3m. The excavation results are consistent with the depth range of the tracer leakage as observed in the images.VISCOUS LIQUID BARRIERThe test site at Brookhaven National Laboratory,located on Long Island,New York,consisted of unconsolidated glacial deposited sediments primarily composed ofﬁne-to coarse-grained quartz sand with some gravel.Groundwater was about 13m below grade(at the base of the ERT image plane).De-tails of this geology and the site characterization are found in Pellerin(1997b).Electrical resistivity of the sands varied between300and 1000ohm-m.Resistivity of the neat colloidal silica(the viscousERT of hydraulic barriers 89liquid)varied,depending on the exact formulation and the curing time.Pellerin (1997b)reports laboratory measurements on the order of 1ohm-m for cured material so the emplaced barrier will produce a strong conductive anomaly relative to the native soils.The plan was to emplace two parallel vertical walls and one sloping wall between them to provide three sides and the bot-tom of the containment structure.A fourth wall (vertical)com-pleted the enclosure.Figure 10illustrates the arrangement (see Pellerin,1997b).Each wall is actually three rows of cylinder-like structures fused together.Each cylinder was formed as the polymer was injected under low pressure from the end of a lance (permeation of the material into the soil),slowly with-drawn from the soil.The primary row of grout cylinders was formed;then a secondary row was placed about 75cm from the ﬁrst;and then the ﬁnal row was emplaced about 75cm from the second row.Although the viscous liquid barrier imaged in this test was excavated,photographs of the structure are of little use since the colloidal silica is transparent and the structure is not self-standing as in the case of the diaphragm wall.Deﬁnition of the wall structure was only possible by measuring electrical conductance of the soil as it was excavated.Therefore,we F IG .6.The 3-D image block,showing the ERT changes in resistivity from baseline during and after the ﬂood test.The ﬁ-nite-difference mesh and the approximate outline of the barrier walls are projected onto the top surface.The ERT boreholes are also shown.(a)The saltwater tracer plume imaged early in the ﬂood between 1130and 1346hours on August 17.Resistivity changes of 30%are shown.(b)The plume imaged at the end of the ﬂood between 1418and 1620hours.Resistivity changes of 35%are shown.(c)The plume imaged on the day after the ﬂood test.Resistivity changes of 35%are shown.have no excavation photographs of the viscous liquid barrier walls.However,we do have other information collected during excavation to compare with the ERT images.The ERT electrode array 5in Figure 10contained 15elec-trodes evenly spaced between 1m and 15m depth.Arrays 1and 4were shorter and had fewer electrodes so as not to inter-cept the barrier once it was emplaced.The strategy with this arrangement of ERT electrodes was to produce a 2-D image of the section deﬁned by the boreholes.The reconstruction mesh contained 15202-D pixels,although only 560deﬁne the image;the others are used to properly model the boundaries.A to-tal of 274transfer resistance measurements were used for the reconstructions (548if reciprocal measurements are counted).Before emplacement of any barrier material,baseline ERT data were taken on June 19,1997,between borehole pairs 1,4,and 4,5.The primary or ﬁrst row of injectate for the slant wall was completed during the last week of July,and on July 31another ERT data set was collected.The remainder of the barrier walls were installed,and on September 19ERT data were collected again.These data allowed for a comparison of the slant-wall images after one row of injectate and with all three rows.Notice that the side walls,already in place dur-ing the September 19data,present high contrast features that。

《基坑工程监测》课件

监测方法
采用全站仪、测距仪等测量仪器，在基坑周边设置测点，定期测量各测点间的距离变化。
数据分析
将测量数据与基准数据进行对比，计算出位移量，绘制位移曲线，分析位移变化趋势。
竖向位移监测
监测目的
了解基坑周边土体在垂直方向上的位移情况，判断基坑的安全性
。
监测方法
在基坑周边设置沉降观测点，定期使用水准仪测量各观测点的高程变化。
智能化监测系统的应用
智能化监测系统能够实现自动数据采集、处理和分析，大大提高了监测效率和准确性。
多参数综合监测
除了传统的位移、沉降监测外，还增加了土压力、水位、孔隙水压力等多参数监测，更全面地反映基坑工程的状态。
远程监控与预警系统
通过远程监控和预警系统，可以实时掌握基坑的状态，及时发现异常情况并采取相应措施，提高了预警和应对能力。
数据分析
将测量数据与基准数据进行对比，计算出沉降量，绘制沉降曲线，分析沉降变化趋势。
深层水平位移监测
监测目的
了解基坑内部土体在水平方向上的位移情况，判断基坑的安全性。
监测方法
在基坑内部设置测斜孔，使用测斜仪定期测量各测点的位移变化。
数据分析
将测量数据按深度进行整理，计算出各深度的位移量，绘制位移曲线，分析位移变化趋势。
合理安排施工顺序，尽量减小对监测的影响，同时调整监测计划以适应施工进度。
监测数据在工程管理中的应用
优化设计方案
根据监测数据反馈的信息，对设计方案进行优化调整，提高工程安全性和经济性。
进度控制与安全管理
利用监测数据指导施工进度，预测可能出现的安全隐患，提前采取措施预防。
ABCD
施工质量控制

基坑监测系统(外文文献) (6)

Professor, Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208, r-finno@ 2 Research Assistant, Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL 60208, m-langousis@ 3 President, GeoEngineers, Inc., Plaza 600 Building, Suite 1700, Seattle, WA 98101 4 Associate, GeoEngineers, Inc., 8410 154th Avenue NE, Redmond, WA, 98052, msmith@ 5 Senior Engineer, GeoEngineers, Inc., Plaza 600 Building, Suite 1700, Seattle, WA 98101, kchin@
Real Time Monitoring at the Olive 8 Excavation By Richard J. Finno1 M.ASCE, Miltos Langousis2, David G. Winter3, M.ASCE, Matthew W. Smith, M. ASCE4 and King H. Chin, A.M.ASCE5
Py of Seattle stipulated that if the lateral movements were observed to be in excess of ½ inch between two successive readings or if the total wall movements exceeded 1 inch, the construction of the shoring wall would be stopped to evaluate the cause of the movement and to establish the type and extent of remedial measures required. Based on past performance data of excavations through similar soil conditions, typical deflections for excavations of this height (Clough and O’Rourke 1990) were expected to vary from 0.001H to 0.003H, or ¾ inch to about 2.5 inches. Therefore particular attention was paid to designing the support system to limit the movements to less than 1 inch. To meet these requirements, the wall adjacent to the Qwest building was designed with a hybrid support system consisting of large soldier piles with tightly spaced soil nails in the upper portion and steeply inclined tieback anchors in the lower portion. To facilitate timely data acquisition and evaluation during construction, a robotic total station autonomously collected 3-dimensional movements of prisms established at the top of the support wall. These data were placed autonomously on a web site that allowed all interested parties access to the information. The total station data were combined with lateral movements behind the support wall measured with conventional inclinometers. Because design calculations suggested the cantilever movements at the top of the wall could likely have been the largest movements that would occur, the combination of the two types of data would allow essentially real time evaluation of the effects of construction on the ground movements. This paper describes the Olive 8 excavation, discusses the design studies used to develop the instrumentation approach, presents the instrumentation and data acquisition systems employed at the site, summarizes the performance of the support system and compares the design predictions with the observed responses. SITE DESCRIPTION The design of the excavation for the 8th and Olive development in Seattle presented a number of challenges due to the presence of the adjacent Qwest building. A 16 ft alley separated the Olive 8 excavation and the Qwest building, immediately to the west. The Qwest building extends approximately 52 ft below grade and is supported on a perimeter strip footing and a mat foundation for the core of the structure. The design bearing pressure of these foundations was 10 ksf. Existing buried power and communications utilities are located in the alley along with five utility vaults. Because of the movement constraints imposed by these conditions, the design of the excavation support for that wall differed from the other three walls. A cross section through the excavation adjacent to the Qwest building is shown in Figure 1. The shoring system for the west support wall consisted of a combination of soldier piles, soil nails and tiedback ground anchors. The soldier piles were W24x162 sections spaced at approximately 8 ft centers. The upper portion of the alley soils was reinforced with a high density soil nail configuration to the elevation where the tieback anchors were installed. Typically, 9 rows of soil nails were installed at 3 ft vertical by 4 ft horizontal spacing. The soil nails were angled 15 degrees below the horizontal

地下室设计深基坑中英文对照外文翻译文献

中英文对照外文翻译(文档含英文原文和中文翻译)Deep E x ca v a t i on sABSTR ACT ：All major topics in the design of in-situ retaining systems for deep excavations in urban areas are outlined. Type of wall, water related problems and water pressures, lateral earth pressures, type of support, solution to earth retaining walls, types of failure, internal and external stability problems.KEYW OR DS: deep excavation; retaining wall; earth p ressure;INTR O DUCTIONN umbe rs of deep e x cavat i on pits i n c ity cent e r s a re incre a sing eve r y year. Buildings, streets surrounding excavation locations and design of very deep basements make excavations formidable projects. This chapter has been or ga n iz ed in suc h a w ay t hat s ubj e cts rel a ted t o deep excava t i o n project s a r e summarized in several sections in the order of design routine. These are types of in-situ walls, water pressures and water related problems. Earth pressures i n c ohesionless and coh e sive soil s are pr e s e nted in two differe nt categories. Ground anchors, struts and nails as supporting elements are explained. Anchors are given more emphasis compared to others due to widespread use obs erve d in the r e cent years. Stability of reta i ning s ystems a re discus s e d a s internal and external stability. Solution of walls for shears, moments, displacements and support reactions under earth and water pressures are obt ained m aking use o f different m e thods of a nalysis. A pile wal l supported by anchors is solved by three methods and the results are compared. Type of wall failures, observed wall movements and instrumentation of deep e xcav a tio n p roj e ct s ar e sum m arized.1. TYPES OF EARTH R ETAINING WAL L S1.1 IntroductionMore than several types of in-situ walls are used to support excavations. The criteria for the selection of type of wall are size of excavation, ground conditions, g roundwate r level, ve rtic a l a nd horizonta l displa c em e nts of adjacent ground and limitations of various structures, availability of construction, cost, speed of work and others. One of the main decisions is the wa t er-t ightness o f wal l. T he foll ow i n g types of in-sit u wa l ls will be summarized below;1.Braced walls, soldier pile and lagging walls2.Sh ee t-piling or s he et pile w a ll s3.Pile walls (contiguous, secant)4.Diaphragm walls or slurry trench walls5.Reinforced concre t e (c as t-i n-s i t u o r pr e f abricate d) r e t ai ni n g walls6.Soil nail walls7.Cofferdams8.J et-gr out and deep mixed w a ll s9.Top-down construction10.Partial excavation or island method1.1.1Br aced Wall sExcavation proceeds step by step after placement of soldier piles or so called king posts around the excavation at about 2 to 3 m intervals. These may be steel H, I or WF sections. Rail sections and timber are also used. At each level horizontal waling beams and supporting elements (struts, anchors,nails) are constructed. Soldier piles are driven or commonly placed in bored holes in urban areas, and timber lagging is placed between soldier piles dur ing the e xc a vatio n. Various det a il s o f pl a c e ment of l a gg ing are a v ailable, however, precast units, in-situ concrete or shotcrete may also be used as alternative to timber. Depending on ground conditions no lagging may be provi ded in relatively shallow pi t s.Historically braced walls are strut supported. They had been used extensively before the ground anchor technology was developed in 1970 s. S oi l s w i t h s om e c ohe s i on and w i thout wat e r table a re us u al l y suitable for t hi s type of construction or dewatering is accompanied if required and allowed. Strut support is commonly preferred in narrow excavations for pipe laying or s i m il a r works but also used i n de ep an d l ar g e ex c avat i on s (See Fig 1.1). Ground anchor support is increasingly used and preferred due to access for construction works and machinery. Waling beams may be used or anchors m a y b e place d di rec t ly on soldier pi l es w i thout a ny beam s.1.1.2Sheet-piling or Sheet Pile WallsSheet pile is a thin steel section (7-30 mm thick) 400-500 mm wide. It is m anufacture d i n different lengt hs a n d sh a pes like U, Z and stra i ght li ne sections (Fig. 1.2). There are interlocking watertight grooves at the sides, and they are driven into soil by hammering or vibrating. Their use is often restricted in urbanized areas due to environmental problems like noise and vibrations. New generation hammers generate minimum vibration anddisturbance, and static pushing of sections have been recently possible. In soft ground several sections may be driven using a template. The end product i s a w aterti g ht s t eel wall i n s oi l. O ne s i de (inner) of wal l is ex ca vate d s t ep b y step and support is given by struts or anchor. Waling beams (walers) are frequently used. They are usually constructed in water bearing soils.S teel s he et pi le s are the mo s t common but som e ti m es rein f orc ed concrete precast sheet pile sections are preferred in soft soils if driving difficulties are not expected. Steel piles may also encounter driving di ff i culties in ve ry de ns e, s t i ff soil s or in soils with boulde rs. Je t ting m ay be accompanied during the process to ease penetration. Steel sheet pile sections used in such difficult driving conditions are selected according to the driving r e s is t ance rather tha n the desi g n mo m e nt s i n the proj e ct. Ano t her fre q uent ly faced problem is the flaws in interlocking during driving which result in leakages under water table. Sheet pile walls are commonly used for t empora r y purposes but pe rm anent cas es are also a bund an t. In tem por ary works sections are extracted after their service is over, and they are reused after maintenance. This process may not be suitable in dense urban e nvironment.1.1.3Pile WallsIn-situ pile retaining walls are very popular due to their availability and practicability. There are different types of pile walls (Fig. 1.3). In contiguous (intermittent) bored pile construction, spacing between the piles is greaterthan the diameter of piles. Spacing is decided based on type of soil and level of design moments but it should not be too large, otherwise pieces of lumps e tc. d rop a n d extra preca u tions are nee de d. Coh es i ve soils or soils ha ving some cohesion are suitable. No water table should be present. Acceptable amount of water is collected at the base and pumped out. Common diameters a re 0.60, 0.80, 1.00 m. W a l ing be am s (us ually call e d …bre a s t in g be a ms ) a r e Tangent piles with grouting in between are used when secant piling or diaphragm walling equipment is not available (i.e. in cases where ground w ater exis t s). P oor w ork ma ns hi p create s significa nt proble m s.Secant bored pile walls are formed by keeping spacing of piles less than diameter (S<D). It is a watertight wall and may be more economical c ompared to di a phragm w all in small to me di um scale ex cava t ion s due t o cost of site operations and bentonite plant.There is also need for place for the plant. It may be constructed“hard-h ard”a s well as “soft-hard”.“S oft”concrete pile cont a ins low c ement content and some bentonite. Primary unreinforced piles are constructed first and then reinforced secondary piles are formed by cutting the primary piles. P i l e c ons t ruc ti on m et hods m a y var y in di f fere nt count ri es for a ll type of p ile walls like full casing support, bentonite support, continuous flight auger(CFA) etc. mostly reinforced concrete but sheet pile sections or steel beams are also used.1.1.4Diaphr agm WallsDiaphragm wall provides structural support and water tightness. It is a classical technique for many deep excavation projects, large civil engineering works, unde r ground car parks, m et ro pits et c. e s pec i ally unde r water table. These reinforced concrete diaphragm (continuous) walls are also called slurry trench walls due to the reference given to the construction technique where exc av a t ion of wal l i s m ad e possible by fi l ling and keeping the wall ca vi ty full with bentonite-water mixture during excavation to prevent collapse of the excavated vertical surfaces. Wall thickness varies between 0.50 m and 1.50 m. The w a ll is c o nstruc t ed pa nel b y p an el i n ful l dept h.Pa ne l le ng t hs are 2 m to 10 m. Short lengths (2-2.5 m) are selected in unstable soils or under very high surcharges. Nowadays depth of panels water stops exceeded 100 m, ex c avati on d ep t hs e xc e ede d 50 m. D i f fere nt pa ne l shapes o t he r t han the conventional straight section like T, L, H, Y, + are possible to form and used for special purposes. Panel excavation is made by cable or kelly supported bu c kets and by a r e cent design c alled …c u t t er o r …hydrof r a i se w hi ch is a pair of hydraulically operated rotating disks provided with hard cutting tools. Excavation in rock is possible. Slurry wall technique is a specialized tec hn i que a nd apart fro m the bucket or t he f rame carrying t h e cutter equipment like crawler crane, pumps, tanks, desanding equipment, air lifts, screens, cyclones, silos, mixers, extractor are needed. Tremie concrete is placed in the slurry starting from the bottom after lowering reinforcementcages. Joint between the panels is a significant detail in water bearing soils and steel pipe, H-beam or water stops are used.1.1.5R einforc e d C onc r ete R eta ining Walls Ex cava ti on i n StagesIt is a common type of staged excavation wall usually supported by ground anchors. Soils with some cohesion are suitable because each stage is f irst excavated be fo re fo r mwork a nd concrete p la cem e nt. No wa t e r table or appreciable amount of water should be present. Sometimes micropile support is given if required due to expected cave-ins.1.1.6S oi l Nai l Wal l sSimilar to the method above excavation is made step by step (1.5 to 2 m high). Shotcrete is common for facing and wiremesh is used. Soft facing is a lso poss i ble making us e of geo t ex t il e s. Ho l e i s dri ll e d, ordina r y steel bars are lowered, and grout is placed without any pressure. Soil should be somewhat cohesive and no water table or significant water flow should be pr e s ent.1.1.7Coffer damsCofferdam is a temporary earth retaining structure to be able to make e xcava t ion for const r uc t ion a c ti vi ties. It is usually preferr ed i n t he coast a l a nd sea environment like bridge piers and abutments in rivers, lakes etc., wharves, quay walls, docks, break waters and other structures for shore protection, large waterfront structures such as pump houses, subjected to heavy vertical and horizontal loads. Sheet piling is commonly used in various forms otherthan conventional walls like circular cellular bodies or double walls connected inside and filled with sand. Stability is maintained by sheeting dr iven de eper than ba s e, sand body between s heet i ng and inside t i e r o ds. Earth embankments and concrete bodies are also used. Contiguous, tangent, secant piles or diaphragm walls are constructed in circular shapes, and no i nte r na l brac i ng or an c horing i s us e d t o form a c o ff e rdam. R einforced concrete waling beams support by arching. Shafts are also made with this method. Large excavations or project details may require additional lateral s upport.1.1.8J et Grout and Deep M ixed WallsRetaining walls are made by single to triple row of jet grout columns or de ep mi x ed col um ns. There is a soil mi x ed wall(S M W) technique s p ecially developed for wall construction where H sections are used for reinforcement. Single reinforcing bar is placed in the central hole opened for jet groutc olum ns. Anchors, nails or struts ma y b e used fo r support.1.1.9Top Down Constr uctionRetaining structure (generally diaphragm wall) is designed and c onstr uc te d a s permane n t l o ad beari n g walls of ba s ement. Piles or barette s are similarly placed to complete the structural frame. Top slab is cast at the ground surface level, and excavation is made under the slab by smaller sized excavators and continued down forming basement slabs at each level. There are special connection details. Top down method is preferred in highlypopulated city centers where horizontal and vertical displacements are very critical, and anchors and struts are very difficult to use due to complex und erg round fa c ilitie s a nd l ifeline str uc ture s and s i t e ope ra tions are di fficult to perform.1.1.10Pa r tia l Excavation or Island M ethodI t i s poss i ble t o give s t ru t support to re tain i ng wa ll s a t a later sta ge aft e r constructing central sections of a building in large size excavations. Core of the structure is built at the central part making sloped excavations at pe ripher a l areas a nd then the c ore f rame is used t o g i ve support t o w alls (Figure 1.9). It may be more practical and construction time may be less compared to conventional braced system. This method may not be suitable in s oft and weak s oi ls du e t o stabi l ity and deformation probl e ms duri n g s l op ed excavations.2.EA R TH P R ESSU R ES ON IN-SIT U R ETAI N ING W A L L S2.1.IntroductionEarth pressures on in-situ retaining walls are rather different than those on ord inary re ta ining wall s due t o the s upporting ele m ents. Fr e e di splace m ent of walls are not allowed. Type of support affects the distribution of earth pressure. Strut loads were measured in strutted excavations in many countries in the past, and recommendations were given. Ground anchor technology is relatively new, and data on instrumented anchored walls for total lateralpressure and for water pressure are being accumulated. Earth pressure diagrams on strutted and anchored walls are expected to be somewhat di ff e re nt due t o s t i ffer s upport condi t ions in t he forme r. T heore t ical approaches will also be discussed.2.2.Ea r th Pressure Distr ibutions on WallsTerz aghi and Peck (1967) and Peck (1969) based on lo a d measurements on struts recommend the pressure distribution shown in Figure 2.1 for cohesionless soils. It is a uniform pressure and given by Eq. 2.1;p = 0.65 K A γt H 2.1where K A is the active earth pressure coefficient, H is the height of wall.Unit weight (γt) is described as the bulk unit weight in the original references.S i nce br a c ed e xcava t ions we r e gene r ally d ewate r e d in the past p r ojec t s the unit weight in the expression was described as wet or bulk. If wall is watertight and water table is present, buoyant unit weight should be usedun de r wa t er table a nd wate r pressure should be a d ded.The rectangular diagram proposed in the figure is not an actual pressure distri b uti on but an e nvel op e obt ai ned by pl ot t i ng t h e me a sured strut l oa ds converted to pressure distribution at each stage of excavation including the final depth covering all distributions. It is also called apparent pressure distribution. It is regarded as a conservative approach because strut loads calculated by such an envelope are generally greater than the measured loads.Rectangular envelope with p = 0.2 γt H is also recommended by Twine and Roscoe (1996) based on more recent field measurements. Similarly use of s ubm er g ed uni t w e i ght below wat e r t abl e a nd add i ti on of wat e r press ure i s recommended. Data on cohesive soils are classified for soft to medium stiff clays and stiff clay.A nc hor or na il supported walls may s how hig h e r l a te r al di s pl a cements, and stress increases at the upper levels of walls may be somewhat less compared to the distributions on strutted walls. However, there are no doc umented c om parisons. In t he soluti o n of a nchored wa l ls b y f init e element, boundary element, finite difference softwares or simpler spring models the analyses may be repeated without assigning pre-tensions initially like in case of nai l s upported walls a nd then a s si g n t he ca l culat e d r e actions a s pre-tensions.There are also recommendations on selection of the type of distribution i n re lation t o h e ight o f br aced walls. Dis t ributions ba s ed on pre s sure cell records are recommended for all heights but distributions by strut load measurements are not found suitable for walls higher than 15 m, they may be us e d for w a ll s of 10 –15 m he i g ht dependin g on c ondi t ions of the g r ound and construction and recommended for heights less than 10 m.Another common case is an alluvial profile where clay, silt, sand layers mixed in different proportions lie in different thicknesses. If a dominant layer is present one of the above distributions may be selected, otherwise atheoretical approach like Coulomb’s earth pressure expression may be followed making use of effective parameters, submerged unit weights and a dd e d wat e r pr essure.Effect of different surcharge loads on walls may be calculated by stress distributions in elastic medium (e.g. NAVFAC 1982). For the upper limit of ve r y rig i d wal l s the distributions are doub l ed. W ide s ur charge loa ds m ay a lso be converted to equivalent heights of soil layer.3.SUPPORTING EL EM ENTS3.1Ground A n chor s3.1.1IntroductionGround anchor is a common type of supporting element used in the de sign and const r uction of in-situ r e t ain i ng w al ls. It i s an inst al la t ion that i s capable of transmitting an applied tensile load to a load bearing stratum which may be a soil or rock. A summary about ground anchors will be given i n this s e ct i on. Typ e s, ca pa city, de s ig n, construction a nd qual it y c ontrol w ill be reviewed.3.1.2Types and C apa city of Anchor sTem porary anc h or a nd perma ne n t a nc ho r are the main types and as the names imply the former is used in temporary works and usually a period of maximum two years are assigned as the design life. Design life of a permanent anchor is the same as the life of structure. Corrosion protection details and factors of safety are the main differences between the two types.Free length is a function of height of the wall. Fixed length is selected according to type of soil and it varies between 3 m and 10 m. Fixed length is t he t ensile load bea r ing part of a n anc hor in s oi l. The r e a r e diff e rent mechanisms of stress transfer from the fixed anchor zone to surrounding ground. It is usually referenced as …bond stress and depends on soil type a nd gr out in g pro c edure. Except i ng sp e cia l c on struct i ons i n f i xe d pa rt of anchors like under reams in stiff clays, jet grouted bodies or inflated aluminum bags, most common type of construction is cement (and water) g rout wi t h som e ad dit i ves. V ery stiff, hard so i ls and ro m an c hettecks m ay be grouted without pressure. Many soils may be grouted but grouting pressure,water cement ratio (w /c) and additives play major role depending on the permea bi lity and s tif f nes s of the soil. Fi x ed le n gt h of ancho r enlarges i n diameter with increasing grout pressure. Grout permeates or fractures or pushes the soil around depending on type of soil, grout and pressure level. Coars e and fine g r a ined gra nul a r s oi ls, alluvi a l soil s a nd we a k r oc ks are generally grouted with several bars of pressure through casing or using packer. Stiff cohesive soils and fine cohesionless soils may be grouted at hig he r press ur es (greater t han 15-20 b ars) to for m hi ghl y f r actur e d larger fixed end bodies to obtain higher capacities. Post-grouting techniques through tube and manchette (sleeve tubing) or double/triple tubing are used. Main possibilities in failure of a single anchor are failure of ground/grout interface, tendon itself or grout/tendon interface.Capacity of anchors in cohesionless soils depends on average grain size (D50), uniformity coefficient (CU), relative density (RD), diameter of drill hole, method of grout injectio n (pr i m ary/sec on dary) and g rout pre s sure.Higher D50, CU, RD and grout pressure result in higher capacities. Fixed lengths of 4 to 8 m are in use and 6 m seems to be a lower limit of r e comme nda ti on for fine to m e dium sands, and the lower limit may be l e s s for gravelly soils. Permeability and grout characteristics (i.e. water-cement ratio, pressure) are key factors for capacities. At lower pressure levels (less than 1 M P a) a nd higher p ress u re s (more t h an 2 MPa) capacit i es fr om 400/500to 1400/1700 kN are observed in fine to medium sands and dense coarser sands and gravels respectively. This wide range is due to enlargement of the dr i ll hole an d m o re grout i n trusion in coarser soil s. Cal cu lat i ons by s oi l mechanics principles cannot explain these capacities. Best way is to perform tests on design anchors.L oa d c a pac i ty of anc ho rs in cl a ys is low c om pared to sandy a nd grave l ly soils. Fixed anchor lengths in design are usually 7-8 m. Application of low grouting pressure (less than 1 MPa) and use of casing tubes may be beneficial to t he capacity. Casin g tube s a lso prevent f ormation of r e mol de d soft cohesive film on borehole surface in layered soils which reduces capacity significantly. Capacity of anchors can be increased in stiff fissured clays using high pressure grouting and post-grouting. High pressure causes hydrofracturing and/or penetration of grout into existing fissures. Using bellsor under-reams in the fixed anchor zone in stiffer clays (cU>90 kPa) also increases capacity. Tremie grouted straight shafts in very stiff or hard soils yiel d suffic i ent c ap acities s i milar to anch or s in rock. Skin fric t ion (m) increases with decreasing plasticity and increasing consistency ((w L- w)/IP). m range is from 50 to more than 400 kPa in stiff clays. Pressure grouting is a lso used in rock. Skin fric t ion or bond v al ues f or va riety of r ocks c an be found in BS(8081) and other references.Grout is in tension like the tendon, and it is assumed that ultimate bond s t re ss bet w een g r out and te ndon is uni f orm. For c lea n stra n ds and defor m ed bars a limit of 2 MPa is recommended. Bond strength can be significantly affected by the surface condition of the tendon, particularly when loose and l ubric ant ma t eri a ls or loose rus t, soil, p ai nt ar e pr es e n t a t t he i nt e rfac e. Minimum grout compressive strength of 30 MPa is recommended prior to stressing. At grout/encapsulation interface maximum ultimate bond is taken 3 M Pa. Enc a psulations are usua l ly used i n permanent an c hor appl i cations against corrosion, and single or double (concentric) corrugated plastic or metal ducts cover single or multi-unit tendons and grouted. Details at head, fr ee l e ngth, seal b et w een fre e and fi x ed len g ths and fixed le ng th vary in m a ny different patented designs (See for example FIP,1986).3.1.3Planning of Anchor sFree length at each excavation stage and fixed length are selected. Fixed length in cohesionless and cohesive soils has been discussed in the previoussection. It is usually kept constant in a project. Fixed length has to be placed outside the active wedge behind wall. It is customary to add an extra to free l ength. Thi s is e s pe c i al l y useful i n projec t s i n stiff cl a ys where deformations at the back of wall extend to distances three times the depth of excavation. Minimum spacing of anchors should be 1.5-2 m and minimum distance of 2-3 m should b e provided between the fixed l e ng ths. A n an c hor d ensity of3-8 m2/anchor generally observed in projects depends on factors such as water pressure, type of soil, depth of excavation etc. If closely spaced a nchor s a re use d ei t her a dj a cent anchor s are de s igned a t di fferent angles w i t h the horizontal like 10°and 15°or identical rows are not used. Angles between 5°and25°w ith the horizontal are normally selected unless fixed l eng t hs ar e locat e d in deeper c o m petent laye r s. Two anchors may be pla c ed at the same anchor head at different angles if required. It is considered a good practice to design positions of fixed lengths in a disorderly manner. Another r e com me nd ati o n i s to k ee p the whole f i x ed length i n a s ingle la ye r i n layered soils if possible. Distance of fixed length to any adjacent foundation/underground service is recommended 3 m minimum. Spacing of a nchors is c ont rolle d by type of wall, and vert i c a l dista nc e betwee n rows is determined by a trial and error process (i.e. anchor capacity vs. spacing, reaction forces etc.).深基坑工程摘要本文概述了城市中保留原址的深基础连续墙系统。

深基坑中基坑监测技术的应用

深基坑中基坑监测技术的应用摘要：基坑监测技术是深基坑施工技术的重要组成部分。

要借助各种监测技术，对深基坑支护结构变形进行监测，形成合理有效的监测系统，有效地提升深基坑施工的安全性以及稳定性，以全面提升深基坑施工的质量及效率。

关键词：深基坑；基坑监测技术；应用探讨引言基坑工程的施工风险系数较高,尤其是深基坑,一旦发生基坑坍塌事故,就可能造成无法挽回的损失。

因此,国家和建筑行业对基坑工程的施工质量和安全管理给予了极大的关注,并采取了多种措施来保证基坑施工质量与安全。

在当前的基坑监测工作中,大多数监测单位仍然采用传统的人工监测方式,这种监测方式成本高、效率低,容易受人为等因素的干扰。

有时候,人工操作会造成数据失真、监测数据难以及时共享等问题。

而将自动化监测系统与云平台等新技术结合在一起,可以实现监测技术的简单化,这也是基坑监测技术的重要发展趋势。

本文对基坑监测技术应用现状与发展方向进行了探讨。

1深基坑中基坑监测技术的应用现状1.1水平位移监测技术的应用（1）全站仪监测技术。

全站仪的全称是全站型电子速测仪,它是由机械、光学、电子元件等组成的测量仪器,可以对水平角、竖直角、斜距、平距以及高程的测量数据进行处理。

因为该测量仪器只需要安置一次就可以完成测站上所有的测量工作,所以被称为全站仪。

全站仪普遍应用于基坑水平位移监测中,其监测方法主要有极坐标法、小角法、自由设站法等。

其中,极坐标法是常用的测量方法,自由设站法能够解决不通视的问题。

近年来,随着全站仪测量精度的不断提高,加上测量理论的创新发展,人们在基坑竖向位移监测中也引入了全站仪进行监测。

相关的研究理论和测量实践也证明了全站仪监测技术的实用性。

（2）激光扫描仪监测技术。

随着科学技术的发展,借助激光扫描仪进行水平位移监测的技术在实践中逐步崭露头角。

在应用激光扫描仪监测技术的过程中,工作人员需要按照激光测距的基本理论,通过向被监测对象发射激光来获得反射信号,然后从反射信号中获取高密度点云数据,进而依照数据进行三维模型重构。

基坑规范英文版

基坑规范英文版篇一：行业标准中英对照44项工程建设标准（英文版）目录123篇二：地下室设计深基坑中英文对照外文翻译文献中英文对照外文翻译(文档含英文原文和中文翻译)Deep ExcavationsABSTRACT ：All major topics in the design of in-situ retaining systems for deep excavations in urban areas are outlined. Type of wall, water related problems and water pressures, lateral earth pressures, type of support, solution to earth retaining walls, types of failure, internal and external stability problems.KEYWORDS: deep excavation; retaining wall; earth pressure;INTRODUCTIONNumbers of deep excavation pits in city centers are increasing every year. Buildings, streets surroundingexcavation locations and design of very deep basements make excavations formidable projects. This chapter has been organized in such a way that subjects related to deep excavation projects are summarized in several sections in the order of design routine. These are types of in-situ walls, water pressures and water related problems. Earth pressures in cohesionless and cohesive soils are presented in two different categories. Ground anchors, struts and nails as supporting elements are explained. Anchors are given more emphasis pared to others due to widespread use observed in the recent years. Stability of retaining systems are discussed as internal and external stability. Solution of walls for shears, moments, displacements and support reactions under earth and water pressures are obtained making use of different methods of analysis. A pile wall supported by anchors is solved by three methods and the results are pared. Type of wall failures, observed wall movements and instrumentation of deep excavation projects are summarized.1. TYPES OF EARTH RETAINING WALLS1.1 IntroductionMore than several types of in-situ walls are used to support excavations. The criteria for the selection of type of wall are size of excavation, ground conditions, groundwater level, vertical and horizontal displacements of adjacent ground and limitations of various structures, availability of construction, cost,speed of work and others. One of the main decisions is the water-tightness of wall. The following types ofin-situ walls will be summarized below;1. Braced walls, soldier pile and lagging walls2. Sheet-piling or sheet pile walls3. Pile walls (contiguous, secant)4. Diaphragm walls or slurry trench walls5. Reinforced concrete (cast-in-situ or prefabricated) retaining walls6. Soil nail walls7. Cofferdams8. Jet-grout and deep mixed walls9. Top-down construction10. Partial excavation or island method1.1.1 Braced WallsExcavation proceeds step by step after placement of soldier piles or so called king posts around the excavation at about 2 to 3 m intervals. These may be steel H, I or WF sections. Rail sections and timber are also used. At each level horizontal waling beams and supporting elements (struts, anchors,nails) are constructed. Soldier piles are driven or monly placed in bored holes in urban areas, and timberlagging is placed between soldier piles during the excavation. Various details of placement of lagging are available, however(来自: 小龙文档网:基坑规范英文版), precast units, in-situ concrete or shotcrete may also be used as alternative to timber. Depending on ground conditions no lagging may be provided in relatively shallow pits.Historically braced walls are strut supported. They had been used extensively before the ground anchor technology was developed in 1970?s. Soils with some cohesion and without water table are usually suitable for this type of construction or dewatering is acpanied if required and allowed. Strut support is monly preferred in narrow excavations for pipe laying or similar works but also used in deep and large excavations (See Fig 1.1). Ground anchor support is increasingly used and preferred due to access for construction works and machinery. Waling beams may be used or anchors may be placed directly on soldierpiles without any beams.1.1.2 Sheet-piling or Sheet Pile WallsSheet pile is a thin steel section (7-30 mm thick)400-500 mm wide. It is manufactured in different lengths and shapes like U, Z and straight line sections (Fig. 1.2). There are interlocking watertight grooves at the sides, and they are driven into soil by hammering or vibrating. Their use is often restricted in urbanized areas due to environmental problems likenoise and vibrations. New generation hammers generate minimum vibration anddisturbance, and static pushing of sections have been recently possible. In soft ground several sections may be driven using a template. The end product is a watertight steel wall in soil. One side (inner) of wall is excavated step by step and support is given by struts or anchor. Waling beams (walers) are frequently used. They are usually constructed in water bearing soils.Steel sheet piles are the most mon but sometimes reinforced concrete precast sheet pile sections are preferred in soft soils if driving difficulties are not expected. Steel piles may also encounter driving difficulties in very dense, stiff soils or in soils with boulders. Jetting may be acpanied during the process to ease penetration. Steel sheet pile sections used in such difficult driving conditions are selected according to the driving resistance rather than the design moments in the project. Another frequently faced problem is the flaws in interlocking during driving which result in leakages under water table. Sheet pile walls are monly used for temporary purposes but permanent cases are also abundant. In temporary works sections are extracted after their service is over, and they are reused after maintenance. This process may not be suitable in dense urban environment.1.1.3 Pile WallsIn-situ pile retaining walls are very popular due to their availability and practicability. There are different types of pile walls (Fig. 1.3). In contiguous (intermittent) bored pile construction, spacing between the piles is greater篇三：基坑开挖换填施工方案英文版Sokoto Cement Factory Project of the 17 Bureau, Chinese Railway ConstructionCompanythConstruction Schemes for Foundation pit ExcavationAnd ReplacementComposed by：Editor：Chief editor：Fifth division of 17th Bureau of CRCC, manager department of theSokoto Cement Factory Project, Nigeria23th November 2104Contents1Introduction ......................................... ...................................................... ............................. １1.1 Basis for theposition ............................................. ............................................... １1.2 Principles for theposition ............................................. ........................................ １2.1Location ............................................. ...................................................... .................... １2.2 Geographicreport ............................................... ...................................................... ... ２2.3 Ground water and undergroundwater. ............................................... ......................... ２ Construction techniques andmethods .............................................. ...................................... ２3.1 Excavation of the foundationpit .................................................. ................................ ２3.1.13.1.23.1.33.1.43.1.53.1.63.23.2.13.2.23.2.33.2.44 Gradient of the foundationpit .................................................. ......................... ３ The stability of the side slope ................................................ ............................ ３ The form ofexcavation ........................................... .......................................... ４Preparation for theexcavation ........................................... ................................ ５ Construction procedures ........................................... ......................................... ６Methods .............................................. ...................................................... ......... ６ Constructionmaterial ............................................. ........................................... ７Constructionpreparation .......................................... ......................................... ８Techniques and constructionalprocedure. ........................................... ............. ８Methods .............................................. ...................................................... ......... ９ 3 Gravelreplacement .......................................... ...................................................... ...... ７ Organization of construction and logistic work ................................................. ................ １１4.1 The managing system for construction organization. ........................................ ...... １１4.2 Human resources for theconstruction ......................................... ............................ １１4.3 Logisticwork ................................................. ...................................................... .... １２4.4 Technicalguarantee ............................................ ..................................................... １２4.5 Quality and techniques standard andregulation ........................................... ........... １２4.5.14.5.24.5.34.5.44.64.6.14.6.24.6.34.74.8 Qualitystandard ............................................. ............................................... １２Quality monitoringorganization ......................................... .......................... １３ Raising awareness for the importance of quality and professional skills. .... １３ Establishing quality managementcode. ................................................ ........ １３ Safety regulations for mechanical construction ......................................... ... １４ Trafficregulations ......................................................................................... １５Safety regulations for fillingconstruction. ........................................ ............ １５ Safety techniquesmeasures ............................................. ........................................ １４Environment protectionmeasures ............................................. .............................. １６ Construction during the rainseason ............................................... ......................... １６4.8.14.8.2 Collecting weatherdata ................................................. ................................ １６ Technical measures fordrainage ............................................. ...................... １６4.9 Technical measures for sandstorm ................................................ .......................... １７4.10 Contingencyplan ................................................. .................................................... １７Construction Schemes for Foundation pitExcavation And Replacement1 Introduction1.1 Basis for the position1.1.1 1.1.21.1.3 Drawings submitted by the Owner (GB50300-2001）。

地铁车站深基坑大学毕业设计(含外文翻译)

地铁车站深基坑大学毕业设计(含外文翻译)地铁车站深基坑大学毕业设计(含外文翻译) 摘要毕业设计主要包括三个部分，第一部分是上海地铁场中路站基坑围护结构设计；第二部分是上海地铁场中路站基坑施工组织设计；第三部分是专题部分，盾构施工预加固技术研究。

在第一部分基坑围护结构设计中，根据场中路站基坑所处的工程地质、水文地质条件和周边环境情况，通过施工方案的比选，确定采用地下连续墙作为基坑的围护方案，支撑方案选为对撑，从地面至坑底依次设四道钢管支撑，并进行围护结构及支撑的内力计算、相应的强度和地连墙的配筋验算以及基坑的抗渗、抗隆起和抗倾覆等验算。

第二部分的施工组织设计，根据基坑围护方案、施工方法和隧道周边的环境情况，对施工前准备工作，施工场地布置，围护结构施工、基坑开挖与支撑安装等进行设计，并编制了工程进度计划，编写了相应的质量、安全、环境保护等措施。

第三部分专题内容是盾构施工中的预加固技术研究。

针对工程施工中的地质条件和施工工况，总结了盾构施工中的土体预加固的技术措施和相关的参考资料，提出在盾构施工中土体预加固的技术措施。

关键词：基坑；地下连续墙；施工组织；支撑体系；盾构预加固技术目录第一部分上海地铁场中路站基坑围护结构设计1 工程概况1 1.1工程地质及水文地质资料1 1.2工程周围环境2 2 设计依据和设计标准4 2.1 工程设计依据4 2.2 基坑工程等级及设计控制标准4 3 基坑围护方案设计5 3.1基坑围护方案5 3.2基坑围护结构方案比选6 4 基坑支撑方案设计8 4.1支撑结构类型8 4.2支撑体系的布置形式8 4.3支撑体系的方案比较和合理选定10 4.4基坑施工应变措施10 5 计算书12 5.1 荷载计算12 5.2 围护结构地基承载力验算14 5.3 基坑底部土体的抗隆起稳定性验算14 5.4抗渗验算15 5.5抗倾覆验算16 5.6整体圆弧滑动稳定性验算17 5.7围护结构及支撑内力计算17 5.8 支撑强度验算21 5.9 地下连续墙配筋验算23 6 基坑主要技术经济指标25 6.1 开挖土方量25 6.2 混凝土浇筑量25 6.3 钢筋用量25 6.4 人工费用25 第二部分上海地铁场中路站基坑施工组织设计 1 基坑施工准备25 1.1 基坑施工的技术准备25 1.2 基坑施工的现场准备25 1.3 基坑施工的其他准备27 2 施工方案29 2.1 概况29 2.2 施工方法的确定29 2.3 施工流程32 2.4 质量控制35 2.5 施工主要技术措施37 2.6关键部位技术措施39 3施工总平面布置40 3.1 施工现场广场临时建筑物的布置原则及位置40 3.2 施工用的临时运输线路的布置40 3.4 建筑材料的堆放位置40 4施工进度计划及管理措施41 4.1 工程安排原则41 4.2施工进度计划41 4.3 施工质量过程控制42 5质量、安全、文明管理措施43 5.1 质量管理措施43 5.2 土方运输环境管理规定44 5.3 安全生产管理措施44 5.4 文明施工措施44 第三部分盾构施工中的预加固技术研究1概述47 1.1盾构法概述47 1.2盾构法的施工条件47 1.3 盾构施工工艺47 1.4盾构法施工的优缺点49 1.5盾构法施工预加固的必要性49 2 盾构施工预加固技术50 2.1概述50 2.2冻结法50 2.3 注浆法51 2.4高压旋喷桩52 3 水平冻结法在盾构进洞中的应用54 3.1 工程概况54 3.2周边环境状况54 3. 3地基加固方式的选择54 3. 4水平冻结法地基加固施工54 3.5冻结加固的效果56 3.6盾构进洞存在的风险57 3.7盾构进洞的保证措施57 4.小结59 参考文献60 第四部分外文翻译翻译原文62 中文译文66 致谢88 第一部分上海地铁场中路站基坑围护结构设计XX大学20XX届本科生毕业设计第26页1 工程概况上海地铁七号线一期工程二标段场中路站位于沪太公路南侧和大场税务所东侧。

基坑监测系统(外文文献) (8)

GEOPHYSICS, VOL. 60, NO. 3 (MAY-JUNE 1995); P. 886-898, 15 FIGS.Cross-borehole resistivity tomography of a pilot-scale, in-situ vitrification testB. R. Spies* and Robert G.ABSTRACTDirect current (dc) cross-borehole resistivity mea-surements were used to monitor the melting andsolidification processes of an in-situ vitrification (ISV) experiment at Oak Ridge National Laboratory (ORNL) in Tennessee. Six boreholes, 6-m deep, were augured around the ISV site, and five electrodes implanted in each hole. Three sets of crosswell, pole-pole resistivity data were collected: prior to the melt phase, immediately after power shut-off, and after themelt zone had solidified and returned to ambienttemperature. These three sets of data were invertedusing a conjugate-gradient scheme to produce conduc-tivity images of the melt phase and the vitrified endproducts.The images obtained depend quite strongly on themodel weighting function applied to the inversion.With an optimum weighting function based on a priorispatial constraints, the resistivity images delineate themelt zone and provide a reasonable indication of itsgeometry. The resistivity data support, but do notrequire, the existence of the melt zone.INTRODUCTIONIndustrialized nations are faced with increasing amounts of toxic and nuclear waste arising from commercial and military development. The U.S. Department of Energy (DOE) is funding various research efforts aimed at evaluat-ing safe remedial alternatives. Of particular interest are techniques for containment of radioactive waste buried in pits and trenches during the past 40 years as a byproduct of the U.S. government’s domestic energy and military pro-gram. The high radioactivity of these materials precludes excavation, which could potentially release contaminants into the air and endanger personnel.In-situ vitrification (ISV) is one possible remedial technol-ogy that could be applied to wastes in pits and trenches; others include grouting and ground densification. The ISV process, developed by the Pacific Northwest Laboratory (PNL) for DOE, involves placing electrodes in and around the contaminated volume of soil, applying power to the electrodes, and melting the entire mass of soil into a chem-ically homogeneous and durable glassy-to-microcrystalline waste form that is resistant to leaching (Spalding et al., 1992). ,Unfortunately, it is difficult to predict the progress of the melt process. Power must be applied long enough for the melt to encompass all the waste material. The melt temper-ature should be high enough for the melt volume to expand at a reasonable rate, yet low enough to minimize radionu-clide volativity. A remote sensing technique, capable of monitoring the extent of the melt, is therefore highly desir-able.For the pilot-scale study described in this report, direct monitoring of the melt was accomplished by the use of 93 thermocouples and optical pyrometers. in vertical arrays installed during construction of the trench. Thus, the progress and temperature of the melt could be accurately determined. However, during application to an actual waste site, this method of depth monitoring is not feasible because sensors cannot be emplaced in a contaminated site. Other methods, such as monitoring energy usage and performing heat flow calculations, are less desirable than direct moni-toring via geophysical methods.Geophysicists at the University of Tennessee planned to use surface and crosswell seismic techniques to monitor the melt process (Jacobs et al., 1992). In conjunction with the 2-D seismic experiment, we proposed to conduct a low-cost 3-D crosswell dc resistivity survey using off-the-shelf equip-ment borrowed from the University of Tennessee. The resistivity survey was designed to demonstrate what couldPresented at 63rd Annual Meeting, Society of Exploration Geophysicists. Manuscript received by the Editor November 10, 1993; revised manuscript received September 2, 1994.*Schlumberger-Doll Research, Old Quarry Road, Ridgefield, CT 06877-4108.of Geophysics and Astronomy, University of British Columbia, Vancouver, Canada V6T 124.© 1995 Society of Exploration Geophysicists. All rights reserved.886Cross-borehole Resistivity Tomography887be accomplished with inexpensive off-the-shelf resistivity equipment in a short time frame and with low budget, and toassess the applicability of borehole electrical tomography in imaging the ISV process. The electrical resistivity imagingexperiment described in this paper was designed and imple-mented in less than three weeks, a strict timetable dictatedby the imminent ISV pilot.The Pilot-Scale ISV TestA series of seven seepage pits and trenches were used between 1951 and 1966 at Oak Ridge National Laboratory (ORNL) for the disposal of approximately 1.6 x 108 1(4.3 x107 gal) of liquid waste containing I million curies of radioactive material. Figure 1 shows the design of a typical seepage trench. These trenches were located on the peaks ofridges to facilitate seepage of liquids, and filled with crushedlimestone or dolomite. As liquids seeped out, the 137Cs and 90Sr remained in, or in close proximity to, the trenches (cesium is sorbed by the illite-rich soil, and strontium wasmade less mobile by treatment with a highly alkaline solution at the time of disposal). The pits and trenches are now covered with asphalt caps to reduce the flow of precipitation through the waste.ISV is a relatively recent candidate technology for in-situ remedial treatment of waste (Oma et al., 1982). ORNL and Pacific Northwest Laboratories (PNL) conducted a series of pilot-scale “cold” (no radioactive components) ISV tests in 1987 to begin evaluation of the technology. A conceptual sketch of the ISV operating sequence is shown in Figure 2. Gases and particulates produced during the high temperature (1300 to 2000°C) operation are diverted by a hood under aF IG. 1. Design of a typical seepage trench used from 1951-1966 at ORNL. The trench was filled with crushed limestone or dolomite to facilitate seepage. Radionuclides were in-tended to remain within or close to the trenches as liquids seeped out (from Spalding et al., 1992).slight vacuum to an off-gas treatment system that scrubs and collects contaminants released into the off-gas.The 1991 pilot-scale ISV experiment at Oak Ridge was the first to use small, precisely known amounts of radioactive material (mostly 137Cs and 90Sr). The experiment was con-ducted at one-half scale of a typical ORNL trench. To permit emplacement of the temperature sensors, a large excavation, 13.5 m square at the surface and 5.5 m square at a depth of4.3 m, was dug and then backfilled with the sensors in place.A half-scale seepage trench was constructed inside the larger excavation, and a small quantity of radioactive waste sealed in plastic bottles was placed near the bottom of the limestone layer.ISV Pilot-Scale ResultsA photograph of the ISV test site prior to melting is shown in Figure 3. Approximately 28 MW.h of cumulative power was applied to the melt over a five-day period at an average power level of 220 kW. Power was turned off intermittently for seismic measurements and equipment problems. The operating temperature of the melt was approximately 1500°C. At this temperature the viscosity is 100 poise, and convection is the dominant heat transfer process within the melt (Spalding et al., 1992).Accurate estimates of the shape of the melt during the experiment were obtained from the temperature data. Tem-perature gradients within the melt are small, usually less than 100°C over the volume of the melt. However, temper-ature gradients across the melt-soil interface are high; tem-peratures dropped from over 1000°C to 100°C over a distance of only 1 m from the melt-soil contact. A narrow low-pressure (P888Spies and Ellisthe temperature remained at 1145°C for 20 hours as a result of latent heat of crystallization released as the molten product precipitated mineral phases.After several months, the body cooled to near-ambient temperature and drill cores were taken to determine its shape and obtain samples. The final shape was an elongate hemisphere with the central portion 2.6 m deep and the margins 2.1 m deep (Figure 4). The upper surface of the melt subsided 1.5 m below ground surface because of volume reduction during melting of the soil. The solidified product was almost entirely crystalline, although the material around the perimeter was somewhat glassy.Thermal Effects on ResistivityMolten rock is highly conductive. Typical values for basalt, andesite, and obsidian are 3 to 10 S/m at 15OO°C, decreasing to 0.2 to 1 S/m at 1000°C (Murase and McBirney, 1973). Laboratory measurements of electrical conductivity of various mixtures of soil and limestone representative of the pits at the ORNL site are described by Shade and Piepel (1990). Electrical conductivity was measured at the temper-ature at which 100-poise viscosity was achieved: for pure soil the conductivity was 2.8 S/m at 1735°C and for a 50% soil - 35% CaO - 15% Na20 mixture, the conductivity was 11 S/m at 1200°C. The highest conductivity obtained (for a 67% soil composition) was 26 S/m at 1233°C.F IG. 3. Photograph of ISV test site prior to melting. Power is fed to the melt via the four protruding graphite electrodes. Gas and particulates are collected in the off-gas hood and scrubbed to remove contaminants. Six 6-m deep boreholes, each with five electrodes and located in a 12-m diameter circle around the hood, were used for the crosswell resistiv-ity experiment. Progress of the melt was monitored by the use of 93 thermocouples and optical pyrometers placed in vertical arrays during construction of the waste trench (from Jacobs et al., 1992).Initially we assumed that the ISV melt would be a con-ductive target in relation to the background soil and based the presurvey modeling on this supposition. However, more detailed analysis of the thermal and hydraulic regime sur-rounding the melt reveals that the resistivity structure is likely to be much more complex than first supposed. Consider a temperature profile starting at background values (20°C) and moving toward the melt. Initially the resistivities will be typical of the clayey soil in the area, around 200 ohm-m. Contributing to the electrical conductiv-ity of the soil is ionic conduction in the pore water and exchangeable ions on the surface of clay particles. The soil at ORNL is approximately 50% porosity with a water content of roughly 20 wt%. The salinity of the pore waters is low, with an ionic strength of 5 x 10-4 to 10-3 normality, and a resistivity of around 200 ohm-m. A rough composition of the soil is: illite (40 wt%), vermiculite (10 wt%), kaolinite (10 wt%), quartz (30 wt%), and carbonates (10 wt%), with a bulk density of 1.35 g/cm3.Clay conduction takes place by ionization of clay minerals and electrolytic conduction through the double layer on the surface of clay particles. Illite and vermiculite provide the main conduction path since they have the highest concentration of counter-ions of the clay minerals present. The bulk resistivity of soil at ORNL (200 ohm-m) is higher than that expected for clay (1 to 5 ohm-m) because the near-surface soils are partly aerated and poorly compacted, and the high rainfall tends to leach the exchange ions from the clay particles (Keller and Frischknecht , 1966).At some location in the melt profile, the temperature of the soil will begin to rise above background values through thermal conduction from the melt. Water conductivity in-creases with temperature according to Arp’s (1953) equa-tion, by about a factor of 3 from 20°C to 100°C. Clay conductivity is governed by the cation exchange capacityF IG. 4. Three-dimensional plan and cross-section of the thermocouple data at the end of the melt stage. The melt body is approximated by the 1000°C isotherm. The final shape of the body obtained from coring is shown as the transparent white solid. The lighter surface represents the 100°C isotherm around the melt. Graphite ISV electrodes are shown as white rods (from Jacobs et al., 1992).Cross-borehole Resistivity Tomography889and mobility of the double layer. Laboratory studies on the temperature dependence of the exchange capacity of clays generally show only a small dependence on temperature, but a large dependence on ionic mobility. Using empirically derived data from Sen and Goode (1992). the ionic mobility, and hence the electrical conductivity of typical clays, should increase by about a factor of 4 from 20°C to 100°C.A counteracting effect on the increase in electrical con-ductivity of clays with temperature is dehydration. Dehydra-tion of clays involves two aspects: removal of bound and interlayer water at relatively low temperatures (typically below 130°C, and often as low as 40°C, depending on confining water pressure), and dehydroxylation (loss of OH in the clay lattice) at much higher temperatures, typically around 300°C (Grim, 1968; Earnest, 1984). Both illite and vermiculite exhibit considerable dehydration at tempera-tures below 100°C (Grim, 1968), starting at about 40°C. The amount of dehydration depends on the initial saturation and the relative humidity of the surroundings. Thus, as temper-ature is increased from 20°C, we may expect an initial increase in conductivity and then a decrease as the clays start to dehydrate and lose their bound and interlayer water.At 100°C the free water in the pores boils off. Some water is drawn in from regions surrounding the melt through capillary action, but at some point all the water will be boiled off and the temperature will rise rapidly. All bound water and interlayer water will be driven off completely between 120°C and 140°C (see, for example, thermogravimetry experiments in Earnest, 1984), and the resistivity of the soil will rise dramatically. As observed in the ISV test (Jacobs et al., 1992), thermal gradients across the melt-soil interface are high: temperatures measured from thermocouple data dropped from above 1000°C to 100°C over a distance of approximately 1 m from the melt-soil contact. Moving im-mediately adjacent to the melt, electrical conductivity would be expected to rise again at the transition zone, where the soil starts to melt (around 900°C), to its highest values in the melt proper at 1500°C.It is now possible to construct a conceptual resistivity profile as shown in Figure 5. The temperature data were gathered from the thermocouple array mentioned earlier. Resistivity decreases somewhat linearly with temperature to between 40°C and 100°C, then rises linearly with a dramatic increase at 120°C. The resistivity will drop steeply at around 900°C as the soil starts to melt.Thus we see that the resistivity section of the melt and surrounding area is likely to be very complex and difficult to image with a remote sensing geophysical technique.CROSSWELL RESISTIVITY SURVEY Survey DesignInitial modeling of the expected difference in response between premelt and postmelt conditions suggested that the change in dc potential in a crosswell tomographic survey would be very small, of the order of several percent. Optimal survey design and data acquisition procedures were there-fore critical.The short time frame and low budget precluded the construction of a sophisticated multichannel system. In-stead, a single-channel Syscal R2 resistivity system was borrowed from the University of Tennessee. The Syscal R2, manufactured by BRGM, has a rated accuracy of 0.3 to 1%, automatic stacking and self-potential bucking, and a maxi-mum output current of 1 A at a power of 700 W.Survey design was hampered by very strict interpretations of environmental regulations by Martin Marietta Energy Systems. Also, because we were working in a DOE facility in the vicinity of both radioactive and hazardous waste, we were urged to avoid creating more mixed waste. These conditions imposed extra limitations, and we were unable to use traditional nonpolarizing lead electrodes or salt water. We used, instead, copper sheeting as electrodes (far from ideal from an electrochemical viewpoint) and distilled water, supple-mented by timely rain showers, to water the electrodes.Six 6-m deep holes were augered at approximately equidis-tant intervals around the ISV site (Figure 6). The holes were located several meters from the vent hood, resulting in a spacing of 5 to 8 m between adjacent holes and 12 m between opposite holes. Five electrodes were placed in each borehole.F IG. 5. Conceptual temperature and resistivity profile through the melt. (a) cross-section showing electrode loca-tions and isotherms during ISV melt process, (b) tempera-ture and resistivity profile. There is a steep thermal gradient across the melt-soil interface, where temperatures drop from >1000°C to 100°C over a distance of 1 m. The conductive melt is encapsulated by a thin dehydrated shell of very high resistivity.Cross-borehole Resistivity Tomography where the first term represents a data misfit measure, and thesecond represents a model structure measure. The datamisfit measure is the sum, over all data, of the differencesbetween the measured and predicted potentials normalizedby the measurement errors. The second term ensures thatthe final model not only fits the data but is simultaneously assmooth as possible. The parameteris a model weighting function. The param-eter is minimized0), or whether ln isa reference or background model. Typical values of(2)that accentuates model variation in the interborehole region.The scale factor 0.1 controls the maximum amount ofdeviation and andin the referencemodel. The reference model892Spies and Ellispremelt data and were inverted to give models with pre-dicted data having 1 to 2% rms misfit.The melt and postmelt images show large conductivityvariations in the vicinity of the boreholes where the sensi-tivity of the dc resistivity technique is highest. This occurseven though we have forced the data to fit the smoothestmodel=3 m) and suppresses structure ( c = 1) within 1 to 2 m of theboreholes =6 m,Cross-borehole Resistivity Tomography893DISCUSSIONWe should emphasize that inversion of any geophysicaldata is a nonunique process; this is particularly true of dcresistivity. Many models fit the data to the same level ofmisfit. From this perspective, the models shown in Figures 7to 13 are representatives only of a class of possible modelsand cannot be considered definitive. Rather, they are possi-ble models of the earth conductivity distribution consistentwith measured data that minimize the objective function.The weighting functions described by equations (2) to (4)are designed to minimize resistivity variation in the vicinityof the boreholes where sensitivity is very high, and favorstructure between the boreholes in the expected region ofthe melt location. We see, though, that the locations of theboundaries of the structure are strongly controlled by theparticular choice of weighting function.We would expect that decreasing the distance between theboreholes, and adding other electrodes on the surface, inextra boreholes, and at greater depths, would improve theresolution of the image, but the placement and total numberof electrodes is always constrained by operational consider-ations. Certainly an automated multichannel acquisition894Spies and Ellissystem would have speeded up data acquisition time and increased data accuracy. The ultimate resolution of any inverse technique is controlled by the sampling aperture and coverage, as well as by the fundamental physics and non-uniqueness of the measurement. Resolution studies on syn-thetic models often fail to take into account realistic varia-tions in resistivity at or near the electrodes, ignore normal geological heterogeneity, and usually underestimate the op-timum number of electrodes required for adequate coverage. The most important task, from the standpoint of the ISV experiment, is to image the base of the ISV melt. Our results suggest that the existence of the ISV melt is not required by the dc resistivity data, but rather, is supported by it. We can enhance the image by a judicious choice of weighting func-tion, but are unable to accurately map the depth extent of the melt body.To better delineate the base of the highly conductive melt zone, it might be preferable to employ an inductive EM technique because induced currents would not be shielded by the resistive shell. A crosswell EM system operating at high frequencies (tens to hundreds of kilohertz) has a nar-rower sensitivity pattern (Spies and Habashy, this issue) than low-frequency EM or dc techniques and would be expected to provide better focusing and resolution.CONCLUSIONSThe 3-D resistivity tomography experiment was successful in imaging the ISV zone in its various phases of premelt,melt, and postmelt. To obtain an optimal image of the melt zone from the inversion it was necessary to apply a weight-ing function that emphasizes structure in the interborehole region and suppresses artifacts caused by high sensitivity near the electrodes.The ISV melting process results in a very complex con-ductivity profile, which includes a highly conductive melt encapsulated by a thin, but highly resistive shell that results from total dehydration of the soil at elevated temperatures. This resistive zone, in turn, is surrounded by a moderately conductive region where the soil is heated to temperatures below 100°C.The resistivity inversion with a narrow weighting function appears to support a two-zoned resistivity model of the melt phase, but this result is probably an artifact of the inversion process. The image changes substantially as the weighting function is varied. The sensitivity of the images to the choice of weighting function results from nonuniqueness and equiv-alence inherent in resistivity inverse problems.The experiment successfully demonstrated that an inex-pensive off-the-shelf resistivity system could be used toF IG. 11. Vertical north-south slices through the approximate center of the melt with the localized weighting function of equation (3): (a) premelt, (b) melt, (c) postmelt.F IG. 12. East-west slices of the melt model obtained with two different weighting functions. The top and center images are inversions obtained with a broad cylindrical weighting func-tion and misfits of 5.0 and 2.8%. The lower image is the same as that shown in Figure 10b (misfit 1.3%). which was obtained with an elliptical weighting function. The image obtained is closely related to the weighting function used.Cross-borehole Resistivity Tomography895F IG. 13. An inversion of synthetic data from a homogeneousearth model with 5% random noise obtained with the ellip-soidal weighting function used in Figure 10. Only minorartifacts are present. The data misfit is 4.8%.acquire high-quality 3-D resistivity shallow borehole datasuitable for tomographic imaging. However, data acquisitionwith the single-channel resistivity system was slow, and anautomated multichannel system would be preferable.The dc resistivity technique is the simplest electricalmethod that can be used for crosswell imaging. However,any dc method is unlikely to directly detect the melt zonebecause the resistive halo acts as an insulating shield tocurrent flow. An inductive electromagnetic technique oper-ated at high frequencies would be more suitable for directdetection of the conductive melt zone.ACKNOWLEDGMENTSWe thank Gary Jacobs and other staff at ORNL for accessto the ISV site and for their encouragement. The pilot-scaleISV test offered a unique opportunity to field test geophys-ical methods in a controlled geological and experimentalenvironment. We wish to thank Rick Williams at the Uni-versity of Tennessee, Knoxville, who provided the resistiv-ity equipment and supervised the electrode emplacement.Kent Conatser expertly acquired the postmelt data. Wethank Douglas Oldenburg for insights into the dc inverseproblem, and Pabitra Sen, Susan Herron, and RosemaryKnight for discussions of thermal effects on clay mineralogy.Gary Jacobs and Rick Williams suggested improvements inthe text, as did the three reviewers.REFERENCESAPPENDIX A: CORRECTION OF PSEUDO POLE-POLE DATAConsider the model shown in Figure A-1 and consider the(A-2)for the geometry of the ISV experiment, assuming (lower configuration in Figure A-1) will be given by(A-3)which satisfies(B-2)The Green’s function is required to satisfy the same bound-ary conditions as v(x). The solution of (B-l) is given by,potential mea-surements and associated errors are acquired. Let us denotethe measurement locations byandwith twocontributions: a data misfit measure and a model character(smoothness) measure, i.e.,Here the first term is a measure of the misfit between the predicted datais a regularization parameter that controls the trade-off between data misfit and model smoothness represented by the second term. Then, the practical inverse problem is simply given byFind along that search direction. When a minimum is found, a new search direction is chosen. Frequently the gradient of the objective function is used in the generation of a search direction. For example, in the steepest descent algorithm, only the gradient of the objective function at the current model estimate is used in forming the search direc-tion. Alternatively, in the conjugate gradient algorithm, the search direction is chosen to be the component of the gradient of the objective function at the current model estimate conjugate to the preceding search directions. Con-sequently, an efficient method of computing the gradient of the objective function is required.The derivation of the gradient of is particularly straightforward when L is self-adjoint. To simplify the derivation we split the objective function into two parts,First, consider the variation in the data misfit contributionunder perturbations of the model and define[a] [a] and using the Green’s function equa-tion (B-3) yields then using the relationship between the Green’s functionthe differential operator, (B-2), gives to first order,(B-10)Combining the preceding equations yields898Spies and Ellisi.e.,MThe gradient of the total objective function which we denote byissimply the gradient directionwhere W is a linear operator satisfying the necessary condi-tions that a proper norm exists, then the steepest ascentdirection and the gradient direction are related byAssuming that it is possible to define the inverse operator,byoperator would be most appropriate. Given the descent direction it is a straightforward matter to construct a conjugate gradient scheme to optimize (B-4). For a review of optimization methods see Hestenes (1980), and for a more detailed discussion of this inverse problem see Ellis and Oldenburg (1994b).。

基坑监测预警系统的设计与应用

基坑监测预警系统的设计与应用【摘要】本章主要介绍预警系统设计的主要目标、架构、功能实现等内容，并就具体工程展示预警系统的实际应用效果。

【关键词】基坑监测预警系统，预警，管理1 系统设计的总目标本系统建设的总目标是借助物联网、数据仓库和数字建模等信息技术，建设一个覆盖范围较广泛的基坑安全监测预警系统。

该预警系统将对所应用工程的基坑支护结构及周边建筑物、管线位移等进行实时监控并将监测结果进行预警和报警，及时以短信的形式将报警结果发给相关建设方、安全监督机构和建设行政主管部门，并追踪有关监测报警处理情况，使监测结果反馈更具时效性，以便及时采取相应措施，提高险情处理的效率，真正达到防灾减灾。

预警系统建设完成后，将大幅度提高地下工程和深基坑安全质量管理工作的效率和力度，从而实现安全质量管理从被动监控向主动监控、事后处理向事前预防的双转变，确保各责任主体（包括建设单位、承建单位、设计单位、监理单位、施工单位等）的安全质量行为切实可控，在地下工程和深基坑工程建设领域真正实现工程安全质量齐抓共管的局面。

2 系统架构设计系统的架构旨在为目标和功能技术之间搭建起一座桥梁，好的架构可以有效的实现总目标的各项要求。

根据本系统的总体目标要求，本系统的架构主要包含有：机构管理、监测管理、实时监控管理、监督管理、系统管理五个功能模块和数据自动采集客户端。

（1）机构管理：监测机构进行各自的机构信息、人员信息、设备信息登记；登记完成后，主管部门对各机构的机构信息、人员信息、设备信息查询及行为管理，行为管理包括在线查询、实时报警查询、采集异常查询、设备超期查询与设备超期预警功能。

（2）监测管理：监测机构对监测的工程信息进行工程项目登记，包括监测方案上传、测点信息登记；巡检记录登记、简报登记；基坑地理位置查询、原始数据查询；工程报警及报警短信发送。

（3）实时监控：主管部门监控整体的基坑现行情况，可按安监站、监测时间进行查询。

主要内容有：安全状态（当前状态与历史状态）、工程名称、工程地点、地理分布、监测情况及处理情况。

国外基坑工程监测方案现状

国外基坑工程监测方案现状引言随着城市化进程的不断加快，城市基础设施建设大规模开展。

作为城市建设中重要组成部分的基坑工程，其建设质量与安全隐患直接影响到城市居民的生活质量与生命安全。

因此，基坑工程的监测成为了不可忽视的一环，其及时精准的监测数据能够有效降低基坑工程施工风险，保障城市基础设施建设的质量与安全。

本文将对国外基坑工程监测方案现状进行梳理与分析，以期为我国基坑工程监测提供有益参考。

一、国外基坑工程监测方案概述随着科技的不断发展，国外基坑工程监测方案已经不断完善和丰富。

基坑工程监测方案主要包含监测目标、监测方法、监测技术与监测周期，通过对目前国外基坑工程监测方案的研究，其主要包括以下几个方面：1.1 监测目标基坑工程的监测目标主要包括地表沉降、地下水位、支护结构变形、地下管线变化及周边建筑物等。

通过对这些监测目标的及时监测与分析，可以及时预警基坑工程施工过程中可能出现的问题，为工程管理者提供科学依据。

1.2 监测方法国外基坑工程监测方法主要包括传统监测方法与现代监测方法两种。

传统监测方法主要包括地基测斜、地下水位监测、支撑结构变形监测、地下管线监测等，而现代监测方法主要包括激光测距仪、GPS定位技术、遥感技术、物联网技术等。

1.3 监测技术国外基坑工程监测技术主要包括传感器技术、无线通信技术、云计算技术、人工智能技术等。

传感器技术主要包括应变测量传感器、位移测量传感器、压力测量传感器等，无线通信技术主要包括WIFI、蓝牙、NB-IoT等技术，云计算技术主要包括数据存储与处理，人工智能技术主要包括监测数据分析与预警。

1.4 监测周期国外基坑工程监测周期一般设置为每天、每周、每月或每季度不等，根据工程的特点与要求，结合原始数据的量测而确定。

二、国外基坑工程监测方案现状基于国外对于基坑工程监测方案的研究与实践，现主要分析以下几个方面：2.1 美国基坑工程监测方案美国基坑工程监测方案以传统监测方法为主，主要关注基坑开挖引起的地表沉降、地下水位变化、周边建筑物变形等监测目标。

基坑监测信息管理系统设计与开发

基坑监测信息管理系统设计与开发摘要：对基坑监测信息管理系统进行了探究，分析了该系统的总体结构以及数据库设计要点，还论述了该系统的功能模块开发的注意事项。

关键词：基坑监测；信息管理系统；数据库1基坑监测信息管理系统设计传统的基坑监测信息管理方法是应用文件管理模式作业，不过这种方法在实践环节表现出了工作效率低、干扰因素多且数据分析查找难度大的弊端，已经无法适应当前的基坑监测信息管理需求。

因此，相关技术人员应该基于当前基坑监测信息管理工作的实际开展需求和信息技术，构建基坑监测信息管理系统。

在这一环节，技术人员首先要完成的工作就是基坑监测信息管理系统框架体系结构的设计和数据库的设计。

1.1框架体系结构设计。

在设计框架体系结构时，技术人员需要从基坑监测信息管理系统的应用目的和作用角度出发，合理地规划其结构分层，梳理各层级以及前后端之间的关系，进而完成科学设计。

比如，常规的基坑信息管理系统可包括数据库、应用支撑层、应用层和客户端。

为了保证其框架体系结构的合理性，该系统前端显示界面可以采用ArcGISEngine组件开发包搭建，并使用Office系列组件完成二次开发，以便于实现信息的有效处理。

此外，在建立数据库环节，可以应用Geodatabase或MYSQL数据库。

1.2数据库设计。

在数据库设计环节，相关工作人员应该先完成对数据的分类。

应用于基坑监测信息管理系统的数据主要包括基坑基础地理数据、监测点数据和监测数据。

其中，基础地理数据的主要内容是基坑工程周边背景数据。

比如，某基坑工程用地呈长方形，其深度约15m，施工范围南北长度约为150m，东西向长度约为160m，而且基坑所在区域的地质条件较为复杂。

其土层中素填土的平均厚度为1.28m，平均高程为14.5m-16m。

这些数据都属于基础地理输数据，在监测信息管理系统应用环节可发挥重要作用。

基坑监测点数据，包含基坑监测点的分布坐标和布设时间，还有其深度和布设方法等信息。

基坑监测方案(含传感器埋设)

基坑监测方案第一讲概述随着我国城市建设高峰的到来,地下空间的开发力度越来越大，地下室由一层发展到多层，相应的基坑开挖深度也从地表以下5～6m发展到12～13m，个别甚至达到30m。

建筑、地铁、合流污水、过江隧道、交通枢纽、地下变电站等建设工程中的基坑工程占了相当的比例.上海地区建筑物地下室基坑开挖深度已超过25m，地铁车站基坑开挖深度一般在十几米至二十米左右，深的工作井达到30m，顶管工程的工作井开挖深度达到27m，地下变电站开挖深度达34m。

近几年，深基坑工程在总体数量、开挖深度、平面尺寸以及使用领域等方面都得到高速的发展.一、基坑监测的重要性和目的在深基坑开挖的施工过程中，基坑内外的土体将由原来的静止土压力状态向被动和主动土压力状态转变，应力状态的改变引起围护结构承受荷载并导致围护结构和土体的变形，围护结构的内力（围护桩和墙的内力、支撑轴力或土锚拉力等)和变形（深基坑坑内土体的隆起、基坑支护结构及其周围土体的沉降和侧向位移等)中的任一量值超过容许的范围，将造成基坑的失稳破坏或对周围环境造成不利影响，深基坑开挖工程往往在建筑密集的市中心,施工场地四周有建筑物和地下管线，基坑开挖所引起的土体变形将在一定程度上改变这些建筑物和地下管线的正常状态，当土体变形过大时，会造成邻近结构和设施的失效或破坏。

同时，基坑相邻的建筑物又相当于较重的集中荷载，基坑周围的管线常引起地表浅层水的渗漏，这些因素又是导致土体变形加剧的原因。

基坑工程设置于力学性质相当复杂的地层中，在基坑围护结构设计和变形预估时，一方面,基坑围护体系所承受的土压力等荷载存在着较大的不确定性；另一方面，对地层和围护结构一般都作了较多的简化和假定，与工程实际有一定的差异；加之，基坑开挖与围护结构施工过程中,存在着时间和空间上的延迟过程，以及降雨、地面堆载和挖机撞击等偶然因素的作用,使得现阶段在基坑工程设计时,对结构内力计算以及结构和土体变形的预估与工程实际情况有较大的差异，并在相当程度上仍依靠经验。

深基坑工程监测预警系统设计

深基坑工程监测预警系统设计CATALOGUE 目录•引言•深基坑工程监测预警系统概述•深基坑工程监测预警系统设计•深基坑工程监测预警系统应用案例•结论与展望CHAPTER引言研究背景和意义深基坑工程安全问题突出01传统监测方法存在不足02研究意义03目前，国内外学者针对深基坑工程监测预警系统开展了大量研究，主要包括监测数据的采集、处理、分析和预警等方面。

已有的研究成果为深基坑工程监测预警系统的设计提供了重要的理论和实践基础。

研究现状随着物联网、云计算、大数据等技术的不断发展，深基坑工程监测预警系统将迎来新的发展机遇。

未来，深基坑工程监测预警系统将更加智能化、自动化和精细化，能够实现多种监测数据的融合处理和深度挖掘，提高预警准确性和及时性。

同时，随着人工智能和机器学习等技术的不断发展，深基坑工程监测预警系统将能够自动学习和优化模型，提高预测和预警的准确性。

发展趋势研究现状和发展趋势CHAPTER深基坑工程监测预警系统概述监测预警系统组成目的深基坑工程监测预警系统的目的是通过对施工过程的实时监控，获取深基坑工程的地质环境信息、支护结构状态信息、地下水状况信息等，分析这些信息的变化趋势，及时发现可能出现的风险和隐患，采取相应的措施进行防范和控制，确保深基坑工程施工的安全性和稳定性。

意义深基坑工程监测预警系统的意义在于通过对施工过程的实时监控和数据分析，可以及时发现可能出现的风险和隐患，采取相应的措施进行防范和控制，避免或减少深基坑工程施工过程中可能出现的风险和损失，提高工程施工的安全性和稳定性。

研究内容难点监测预警系统的研究内容和难点CHAPTER深基坑工程监测预警系统设计系统架构监测点布设数据采集频率030201系统总体设计传感器类型传感器安装数据采集精度传感器节点设计数据传输方式对采集的数据进行预处理和滤波，去除异常值和噪声，提高数据质量。

数据处理算法数据存储方案数据传输与处理设计预警等级根据预警指标的变化情况，设定不同的预警等级，如一级预警、二级预警等。

智能监测系统在深基坑工程中的应用与前景

智能监测系统在深基坑工程中的应用与前景摘要：本文以包含集电子技术、通讯技术、计算机技术和传感技术的自动化监测系统结合以往深基坑工程施工过程中的重难点管控经验、工艺流程、施工方法、施工管理多种角度，阐述智能监测系统在深基坑工程施工过程中的应用以及对比传统施工方式生产及管理的优势，分析BIM系统在现代化科技的应用，预测智能化未来发展前景。

关键词：深基坑自动化智能监测 BIM系统指导施工引言自动化监控系统是目前我国建筑业信息化发展的主要趋势，也是反映建筑工程监控信息化的深层次价值的重要工具。

安全监控是项目建设中必不可少的一环，建设一套先进的、远程、实时监控系统是建设项目管理的一项重要内容。

随着自动化技术的不断普及，在监控系统中的运用，弥补了以往手工监控的缺陷，为工程建设提供了便利。

1自动化监测系统概述自动监控系统具有实时追踪、监控功能，相对于受环境因素的影响，可实现24小时连续追踪，无外界因素干扰；实现对整个监控、存储的自动化运行，防止人为干扰而导致的误差，从而影响到测量数据的准确性；更加直观地显示了监控的效果，能够使用不同的色彩来显示数据的变化；根据现场情况进行自动调停，及时发现问题，保证工程的安全。

本文以市政工程某地铁项目为例，阐述自动化监测系统在深基坑施工中的具体应用，可实现混凝土养护系统自动养护系统、混凝土自动测温系统、标养室恒温恒湿系统、基坑支护结构内力监测系统、基坑支护结构位移监测系统、地下水位、坑外土体监测系统、节能减排施工环境监测系统，资料智能管理系统，自动化监测与BIM应用，各个方面的智能监测指导现场施工，保证工程质量安全。

图1自动化监测系统图2线上互动体验区2、自动化监测系统与深基坑工程结合应用2.1 混凝土自动养护系统自动养护喷淋系统是采集混凝土结构内部温度和结构所处环境温湿度进行数据对比分析，根据提前设定的温湿度系数联动自动喷淋设备，既节省人工又达到真正实时养护的目的。

喷淋养护移动操作便捷，协同监控管理，利用隔离塑料将结构侧每台设备可按结构侧墙施工段布置，提供web浏览器监控如墙与外界隔离，形成喷养护区域，养护工作结束可轻松将何和手机APP监控系统，淋养护环境设备台车推移至下一结构段实时掌握喷淋养护动态自动化湿度采集全自动化喷淋结构表面温度采集不需要任根据系统设定湿度阈值，控制器根何人工，全自动实时采集当据采集的实时湿度值进行喷淋泵的年湿度值上传至系统启动停止工作。

基坑监测规范

为规范建造基坑工程监测工作，保证监测质量，为优化设计、指导施工提供可靠依据，确保基坑安全和保护基坑周边环境，做到安全合用、技术先进、经济合理，特制定本规范。

本规范合用于建(构)筑物的基坑及周边环境监测。

对于冻土、膨胀土、湿陷性黄土、老黏土等其他特殊岩土和侵蚀性环境的基坑及周边环境监测，尚应结合当地工程经验应用。

建造基坑工程监测应综合考虑基坑工程设计方案、建设场地的工程地质和水文地质条件、周边环境条件、施工方案等因素，制定合理的监测方案，精心组织和实施监测。

建造基坑工程监测除应符合本规范外，尚应符合国家现行有关标准的规定。

为进行建(构)筑物基础、地下建(构)筑物的施工所开挖的地面以下空间。

基坑开挖影响范围内既有建(构)筑物、道路、地下设施、地下管线、岩土体及地下水体等的统称。

在建造基坑施工及使用期限内，对建造基坑及周边环境实施的检查、监控工作。

承受坑侧水、土压力及一定范围内地面荷载的壁状结构。

由钢、钢筋混凝土等材料组成，用以承受围护墙所传递的荷载而设置的基坑内支承构件。

一端与挡土墙联结，另一端锚固在土层或者岩层中的承受挡土墙水、土压力的受拉杆件。

设置在围护墙顶部的连梁。

直接或者间接设置在被监测对象上能反映其变化特征的观测点。

单位时间内的监测次数。

为确保基坑工程安全，对监测对象变化所设定的监控值。

用以判断监测对象变化是否超出允许的范围、施工是否浮现异常。

开挖深度超过 5m、或者开挖深度未超过 5m 但现场地质情况和周围环境较复杂的基坑工程均应实施基坑工程监测。

建造基坑工程设计阶段应由设计方根据工程现场及基坑设计的具体情况，提出基坑工程监测的技术要求，主要包括监测项目、测点位置、监测频率和监测报警值等。

基坑工程施工前，应由建设方委托具备相应资质的第三方对基坑工程实施现场监测。

监测单位应编制监测方案。

监测方案应经建设、设计、监理等单位认可，必要时还需与市政道路、地下管线、人防等有关部门商议一致后方可实施。

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