文字报告-译稿改

TABLE OF CONTENTS1.0 FOREWORD (3)1.1 GENERAL DESCRIPTION OF THE PROJECT (3)1.2 PURPOSE AND TECHNICAL REQUIREMENTS OF THE INVESTIGATION (4)1.3 BASIS FOR THE INVESTIGATION (5)1.4 MEANS AND COMPLETED QUANTITY OF WORK (6)1.5 MEASUREMENT CONTROL SYSTEM (7)2.0 ENGINEERING GEOLOGICAL CONDITIONS OF THE SITE (8)2.1 LANDFORM, TOPOGRAPHY AND SITE ENVIRONMENT (8)2.2 FORMATION AND CHARACTERISTICS OF FOUNDATION SOIL (8)2.3 PHYSICAL AND MECHANICAL PROPERTY INDEXES OF FOUNDATION SOIL (10)2.4 GROUND WATER (11)2.5 CORROSIVE ACTION OF SITE SOIL AND WATER ON BUILDING MATERIALS (11)2.6 ADVERSE ENGINEERING GEOLOGICAL ACTIONS AND BAD OBJECTS BURIEDUNDERGROUND (11)2.7 EARTHQUAKE EFFECT OF THE SITE AND FOUNDATION (11)2.8 EV ALUATION OF SITE STABILITY AND SUITABILITY (12)3.0 GEOTECHNICAL ENGINEERING ANALYSIS AND EV ALUATION (12)3.1 DETERMINATION OF GEOTECHNICAL BEARING CAPACITY PARAMETERS AND DEFORMCALCULATION PARAMETERS OF THE FOUNDATION (12)3.2 DETERMINATION OF BEARING CAPACITY PARAMETERS OF PILE FOUNDATION (13)3.3 FOUNDATION FORM AND ANALYSIS & EV ALUATION OF BEARING STRATUM (14)3.4 ESTIMATION OF BEARING CAPACITY OF SINGLE PILE (15)3.5 FEASIBILITY OF PILE FOUNDATION DRIVING AND ISSUES NEEDING ATTENTIONDURING PILE FOUNDATION CONSTRUCTION (16)4.0 EV ALUATION OF STABILITY OF ARTIFICIAL SLOPE (16)4.1 GEOLOGICAL CONDITIONS OF SLOPE WORKS (16)4.2 GRADIENT OF ROCK MASS SLOPE (17)5.0 CONCLUSION AND SUGGESTION (17)5.1 CONCLUSION (17)5.2 RECOMMENDATIONS (18)Attached drawing序号Drawing name No. pages1 Legend 1 12 Location Plan of Boreholes 2 43 Engineering Geologic Section 3-1～3-5 54 Conventional Consolidation e-p Curve 4-1～4-3 45 Borehole log 5-1～5-16 186 Summary of Results of Soil Experiment6-1～6-2 21.0 ForewordEntrusted by the employer, we undertook the geotechnical investigation of Xiapu Logistics Warehouse Project in its preliminary survey phase.1.1 General description of the ProjectThe proposed project is located at 6km to southeast of Beilun, adjacent to Caiqiao in the east, connected to Jintang Watergate in the north and close to the northern foot of Tiantong Mountain.Fig. 1 Traffic Location Diagram of Proposed SiteFor details of layout and dimensions of the proposed project, see ―Location Plan of Boreholes‖.The proposed project covers land area of 200416.9 square meters, with total building area of 110606.4 square meters, and mainly consists of warehouse, office buildings, and guardhouses. The warehouses are single story buildings, with clear height of 9.0meters, lightweight steel construction, and column bay size is 11.4m×25.5m &11.4m×30m. The office buildings are two-floor construction, with frame structure. The elements of proposed buildings are shown in Table1.Table 1 Summary of Elements of Proposed Buildings (Structures)According to ―Code for Investigation of Geotechnical Engineering‖ (GB50021-2001), importance class of this project is graded as 2, site complexity class is graded as 2 and foundation class is Class 2. Therefore, we determined that the geotechnical engineering survey class is Class B.1.2 Purpose and technical requirements of the investigationPurpose of this investigation is to provide accurate and reliable engineering geological basis and necessary geotechnical parameters for preliminary design of this Project and carry out suitability evaluation of the proposed site to meet the information needed for the preliminary design phase.Tasks and requirements of this investigation are following:1.Preliminarily ascertain the stratum structure, geotechnical engineering feature,landform and topography of the site as well as regularities of distribution &embedding and physics & mechanics property indexes of various geotechnical layers.2.Preliminarily ascertain the formation cause, distribution and size ofadverse geologic actions within the site, predict its development trend and evaluate the site stability.3.Preliminarily ascertain embedment features of the shallow underground water, and toevaluate corrosivity of the groundwater and soil to building materials (reinforced concrete structure and steel structure).4.Determine the possible earthquake intensity of the site, preliminarily classify the sitecategory and to delineate favorable, unfavorable or dangerous areas for earthquake-resistance and analyze & evaluate earthquake effect of the site and ground.5.Evaluate stability and suitability of the site and environment;6. Analyze and evaluate engineering and geographical conditions of the site,propose preliminary scheme of the ground foundation for the proposed buildings, provide ground bearing capacity parameters, analyze influence of foundation construction on the environment and propose prevention and mitigation measures.1.3 Basis for the investigation1. Contract note for geotechnical engineering investigation task2. The main specifications and standards to be executed for this survey are listed as follows:A. ―Code for Investigation of Geotechnical Engineering‖(GB50021-2001) ( Nationalstandard);B. ―Code for Seismic Design of Building‖(GB50011－2001) (National standard);C. ―Code for Design of Building Foundation‖(GB50007－2002)(National standard);D. ―Code for Design of Building Foundation‖(DB33/1001-2003)( Zhejiang provincial standard)E. ―Standard for Soil Test M ethod‖ (GB/T50123-1999)(National standard);F. Technical Standard for Boring of Geotechnical Investigation of Constructions (JGJ87-92)( occupation standard);G. Technical Standard for sampling of undisturbed soils (JGJ89-92)( occupation standard);H. ―Techn ical Code for Building Pile F oundations‖(JGJ94-94)(occupation standard);I.―Standard for Engineering Classification of Rock M asses‖( GB 50218—94) (National standard);J.―Technical Code for Building slope Engineering‖(GB 50330—2002) (National standard);J. Standard for Investigation-documents of Geotechnical Engineering (DBJ10-5-98) (Zhejiang Provincial standard).1.4 Means and completed quantity of workFor this site investigation, boring, sampling and indoor geotechnical tests were carried out. All the work is carried out strictly according to the Documented Procedures and Quality Manual established by us and relevant codes and specifications, and the investigation quality is in compliance with the requirements.The number of exploratory holes was determined through agreement with the employer, and 8 boreholes and 8 cone penetration test (CPT) holes are arranged. During the surveying, as most of the site is backfilled with huge crushed stones and the site is located at low hills and in front of the mountain, CPT is very difficult. After approval of the employer, all the CPT holes were replaced by boreholes. Distance between prospecting lines is 90~140m and distance between prospecting points is not more than 150m. The boreholes are arranged at the corners and edge lines of main buildings and change of engineering geological conditions was controlled all over the site. There is at least one borehole arranged at each topographical unit and unit connection positions on each prospecting line. The boreholes are deep into highly-weathered or moderately-weathered bedrock. After prospecting was completed, hole opening elevation was measured using a leveling instrument.Field work of this investigation was carried out from June 28th 2008 to July 5th 2008, and completed quantity of work is shown in Table 2.Table 2Summary of Completed WorkFor results of this investigation, we used independent coordinate system of Ningbo and 1985 National Elevation Datum.Refer to Table 3 for coordinates and elevation of boreholes and burial depth of groundwater.Table 3 coordinates and elevation of boreholes and burial depth of groundwater2.1 Landform, topography and site environmentSite of this project is 500m long and 400m wide. There are two topographical units within the site, namely low hills and plains on the sea shore. The low hills consist of Late Jurassic volcanic rock which is crystal and vitric welded tuff. The ridge line extends in northwest~southeast direction, with thin average-weathered layer covering on the ridge and thick covering on the two wings. With significant landform fluctuation, the ground level is 4.0~50m. Now the site is an open-air quarry, with exploitation datum surface not lower than original elevation of the adjacent ground surface, without backfilling. Its north is almost flat ground. The artificial exposure on the quarry shows that the rock body is broken and fragmented and is mostly moderately-weathered rock. It is hard rock and moderately-weathered bedrock with uniaxial saturated compression strength exceeding 30MPa.Upper part of the plains on sea shore mainly consist of marine deposit, alluvial deposit and proluvial deposit, with much difference between their thicknesses, especially the thickest in northeast end and southwest end. The ground level is 2.0~3.3m, with flat topography in general. There is soft soil within the ground. Thickness of soft soil layer differs due to its location in the site, and general trend is that the farther from mountain body it is, the thicker the layer of soft soil is.There is a water pond in southwest of the site and it is about 40m long and 20m wide.2.2 Formation and characteristics of foundation soilAccording to the information obtained from this investigation, the prospected depth isdivided into 7 engineering geological layer groups and 12 engineering geological sub-layers (including lenticle) by shallow soil layer according to their difference in origin era, burial conditions, rock characteristics and physical & mechanics property. They are listed as follows in the top-bottom sequence:Layer①1made ground (artificial earth fill of crushed stones):grayish yellow, loose, mainly consisting of block stones, broken stones and a small quantity of clayey soil, with poor size grade distribution and some skeleton frames built on stilts.Layer①2cultivated soil (clayey plain made ground): yellowish gray, plastic, containing a small quantity of plant rootstock and humus, with artificial deposit in some locations.Layer ②silty clay: grayish yellow, plastic, thick-bedded, slightly smooth, with medium toughness and dry strength, containing a small quantity of iron and manganese spots, with slight layering at the bottom.Layer③sludgy clay:gray, very soft, thick-bedded, smooth, with high toughness and dry strength, containing humus and fragmented shells, with homogeneous soil quality.Layer③a silty sand: light gray, slightly dense, thick-bedded, containing a small quantity of clayey soil, only existing in some areas, looking like lenticle.Layer④silty clay: greyish yellow, stiff, thick-bedded, slightly smooth, with medium toughness and dry strength, containing iron and manganese concretion and a small quantity of fine sands.Layer⑤silty clay: gray, soft, thick-bedded, slightly smooth, with medium toughness and dry strength, containing humus, being clayey soil in some locations.Layer⑤a silty sand: light gray, medium dense, thick-bedded, containing a small quantity of clayey soil.Layer⑥clay: greyish yellow, stiff, thick-bedded, smooth, with high toughness and high dry strength, containing iron and manganese concretion, with homogeneous soil quality.Layer ⑦1completely-weathered crystal and vitric welded tuff: grayish yellow, stiff tohard, thick-bedded, containing a lot of stripes in various colors, with weathered rock in some locations. Almost weathered and looking like clay minerals and looking sandy in some locations.Layer ⑦2highly-weathered crystal and vitric welded tuff: brownish yellow, rock core takes the shape of block, fragile when hammering, difficult to drill in, with developed cracks.Layer⑦3moderately-weathered crystal and vitric welded tuff: grayish yellow, consisting of tuff in bock shape, rock core takes the shape of short column, non-fragile when hammering, difficult to drill in, with developed cracks.For the distribution, burial and main characteristics of all the engineering geological layer groups, see the attached ―Engineering Geological Sectional Drawing‖and ―Geological Bar Chart for Boreholes‖.2.3 Physical and mechanical property indexes of foundation soilAccording to the results of geotechnical tests provided by our testing center and by using above-divided foundation soil layers as statistical unit, we checked all the indexes and deleted particular deviated values and unreasonable values before making statistics. Then we made statistics according to Grubbs rules and provide average values of each index, coefficient of variation and sample quantity for statistics.Shearing index is the peak shear strength.Deviated data in the physical and mechanical property indexes of all the layers are deleted using Grubbs method. When the diversity d meets the following expression, this data should be deleted:│ d │ > gδWhere, d=f-f mδ—deviationg—parameter obtained using Grubbs method (when a=0.05)f—test data of physical and mechanical index of soilf—mean value of physical and mechanical index of soilmFor statistical result, see Table 4 ―Statistical Table of Physical and Mechanical Index‖. Figs. 4-1 4-3 ―Routine e-p Curves‖ are mean compression curves of all the layers.For results of routine geotechnical tests of undisturbed samples in lab, see ―Summary of Results of Geotechnical Tests‖.2.4 Ground waterGround water shallower than the prospecting depth within the site is mostly fissure water in bedrock and pore phreatic water. The pore phreatic water mainly exists in the shallow Layers ①, ② and ③. During investigation, burial depth of pore phreatic water is about 0.2～1.4m, and the water level change is mainly controlled by atmospheric water vertically seeping into it and the micro topography. The water level is much related with original landform. There is a lack of fissure water in bedrock, and the shallower or exposed, the shallower the water level is. Phreatic water level changes by 0.50～1.00m annually.2.5 Corrosive action of site soil and water on building materialsThere are no pollution sources or pollution history around the site of proposed project. According to the groundwater quality analysis report for the site area, it is preliminarily determined that groundwater within the site has no corrosive action on concrete and rebars in concrete and has medium corrosive action on steel structures, and the soil has no corrosive action on building materials.2.6 Adverse engineering geological actions and bad objects buried undergroundThe site investigation shows that within the scope to be affected by this project, there are no landslide, collapse, debris flow, geofracture, march and ground sediment or other adverse geological action found, and besides there are no hidden creek or pond underground. There is a water pond of 40m long and 20m wide in the southwest of the site, which has some effects on the project.2.7 Earthquake effect of the site and foundationAccording to 1:4000000 Zoning Map of ground motion parameters of China (GB18306-2001) and Code for Seismic Design of Building (GB50011-2001), seismic peak ground acceleration of this area is 0.10g, and seismic fortification intensity is 7degrees. Saturated silty sands are only sparsely discovered and so earthquake liquefaction may not be taken into account.According to results of wave speed tests for similar ground layers in this area and distribution of foundation soil within the site, relevant provisions of Code for Seismic Design of Building(GB50011-2001)are executed. According to the engineering geological conditions of the site, thickness of the site covering is 0~25m and estimated equivalent shear wave velocity exceeds 140m/s. According to Code for Seismic Design of Building(GB50011-2001) of PRC, the site is Class I ~ II. The areas formed by boreholes Z1, Z2, Z5, Z6, Z10, Z11, Z14, Z15 and Z16, are equivalent to the units with low-hill topography and are Class I, which is favorable to resistance against earthquake. Other areas are Class II, which are adverse to anti-earthquake. Generally, Warehouse 1# is in an area helping anti-earthquake and other buildings are in the areas adverse to anti-earthquake. See Fig.2 for the site category classification.According to Code for Seismic Design of Building(GB50011-2001) of PRC, design earthquake group of this site is Group 3, and design characteristic cycle of the site is 0.35s for Class I areas and 0.45s for Class II areas.2.8 Evaluation of site stability and suitabilityThere are no adverse geological actions affecting site stability within the site, such as carst, earth cave, landslide, collapse, debris flow and active faults. But stability of the artificial slope should be considered. The site has good stability but is a composite foundation of soil and rock. After proper corrective actions are taken, the site is basically suitable to the construction of this project.3.0 Geotechnical Engineering Analysis and Evaluation3.1 Determination of geotechnical bearing capacity parameters and deform calculation parameters of the foundationAccording to the results of geotechnical tests and dynamic penetration tests in the lab for this investigation and site conditions, we calculated and determined characteristic values fak of bearing capacity parameters of various geotechnical layers and deform calculation parameters of the foundation. See Table 5.Table 5 Bea ring Capacity Parameters and Deformation Calculation Parameters Of Of Various Geotechnical LayersBearing capacity parameters of pile foundation are calculated according to the results of geotechnical tests, burial and distribution conditions of all the geotechnical layers and pursuant to Chinese national standard ―Technical Code for Building Pile Foundations‖ (JGJ94-94) and Design Code for Building Foundation of Zhejiang Province (DB33/1001-2003), and are determined with reference to local building construction experience. We now provide characteristic values of skin friction of rock and soil around Cast-in-place pile with driven casing and borehole cast-in-place concrete pile (q sia(kpa)) and characteristic values of rock and soil at pile end (q pa(kpa)) in Table 6.Bea ring capacity parameters of Layer ⑦3 in the table are the values measured when ratio of depth of pile driven into rock to pile diameter is 1. Considering characteristics of this project, there are heaped load around the piles, and if upper soft soil is not consolidated completely, negative friction maybe caused on pile foundation duringoperation, therefore negative friction of Layer ⑤ and upper layers should be taken into account in the foundation design.Table 6Summary of Pile Bearing Capacity ParametersFoundation form should be selected according to topographical unit where the building is, load conditions and deformation requirements.Low-hill area: highly-weathered or moderately-weathered bedrock is exposed above datum surface, with good natural foundation conditions, so general shallow foundation can meet the load and deformation requirements. Hence, for Warehouse 1#, Warehouse 4# and Warehouse 6#, shallow foundation can be applied, with highly-weathered bedrock of Layer ⑦2 or moderately-weathered bedrock of Layer ⑦3 used as foundation bearing stratum. In some areas where bedrock surface is not exposed, manual bored piles or pier foundations can be used.In plain area: as burial depth of underlying bearing stratum changes significantly, and shallow foundation cannot meet the requirements for bearing capacity and deformation, cast-in-place pile with driven casing or borehole cast-in-place concrete pile, dependingon load on a single column and deformation requirement. When load on a single column exceeds 2000KN and there are high deformation requirements, borehole cast-in-place concrete pile can be used, with highly-weathered bedrock of Layer ⑦2 or moderately-weathered bedrock ⑦3 used as foundation bearing stratum. The pile diameter can be determined according to load conditions and the pile end should enter into the bearing stratum by 1×pile diameter or more. However, only increasing the depth of pile entering into rock is not correct, and this depth value should ensure that capacity of foundation soil bearing the piles match with the pile strength. Diameter of cast-in-place pile with driven casing can be Φ377mm or Φ426mm, and c layey soil of Layer ⑥or completely-weathered bedrock of Layer ⑦1 can be used as bearing stratum for pile end. Accessory buildings such as office building and gate guard house can be built on natural foundation, with silty clay of Layer ②used as bearing stratum for natural foundation. Water pond area and other low areas can be treated using soil replacement cushion method.Loads on the warehouse floors are unknown so far. If the load is great, it is necessary to take into account the floor damages and differential settlement caused due to difference between bearing capacities and between deformation characteristics, and foundation treatment should be carried out for soft soil if necessary.3.4 Estimation of bearing capacity of single pileCharacteristic values of vertical bearing capacity of single piles are calculated according to Table 6 ―Summary of Pile Bea ring Capacity P arameters‖and by selecting typical prospecting boreholes. The result is shown in Table 7.Note: 1. Friction of made ground layer is not taken into account for estimation of characteristic values of bearing capacity of single pile2. Structural strength of pile is not taken into account for estimation ofcharacteristic values of bearing capacity of single pile.3.5 Feasibility of pile foundation driving and issues needing attention during pile foundation constructionThis project is far from central zone of the town. Its site is clear and surrounding environment is not sensitive to noise and vibration.Precautions during driving borehole cast-in-place piles into rock: select Layer ⑦3 as pile end bearing stratum and correct hole protection with mud should be carried out during piling to prevent collapse of upper soil. Besides, thickness of slag deposit at the hole bottom should be controlled and mud clearing and transport should be carried out correctly. Ensure that full cross-section of pile end enters into moderately-weathered bedrock by 0.5m or more.Precautions during construction of cast-in-place pile with driven casing: when the casing is driven through weak and soft soil layer, it should be pulled up while it is vibrated, and the pulling speed should be controlled strictly. Or otherwise possible diameter reduction and breaking of pile will be caused. The rebars should be long enough to go through sludgy clay of Layer ③.4.0 Evaluation of Stability of Artificial SlopeThe mountain in the south of the site can be used as construction site only after artificial treatment, and then an artificial slope of as high as 40m or so will be formed. According to ―Technical Specifications for Architectural Side Slope Engineering‖, the slope should be Class A safety.4.1 Geological conditions of slope worksHardness of rock: the rock gives out ringing sounds when hammering, with slight rebounding, and hands feel a little vibration. The rock is difficult to break into pieces and is hard rock, mostly moderately-weathered, with saturated uniaxial compressive strength >30MPa.Weathering extent: the structure construction is partially damaged, mineral color changes significantly, and weathered minerals appear or weathered interbedded stratum exists on the fissure plane. So the weathering extent is medium weathering.Rock mass integrity: developed to Groups 2~3 on constructional surface, with average binding between main constructional surfaces. The rock is broken rock.According to above-mentioned qualitative characteristics of rock mass, preliminary determination of basic quality class of the rock mass is Class IV.4.2 Gradient of rock mass slopeAccording to the weathering extent of the slope rock mass disclosed by artificial exposure, development characteristics of discontinuous constructional surfaces and slope height, and pursuant to requirements of applicable code and specifications, our preliminary advice is that gradient of moderately-weathered bedrock slope should be about 1:0.75, and that of highly-weathered bedrock slope should be about 1:1.5.0 Conclusion and Suggestion5.1 Conclusion1. This site investigation ascertained burial and distribution law of all the geotechnical layers shallower than 40.0m within the site and provides physical and mechanical property indexes and foundation bearing capacity parameters of each layer. This report can be used as engineering geological basis for design of construction drawings and next geotechnical investigation for the proposed project.2. The soil mass with prospecting depth less than 40.0m within the site is divided into 7 engineering geological unit layers and 12 engineering geological sub-layers (including lenticle) by shallow soil layer according to their difference in origin era, burial conditions, rock characteristics and physical & mechanics property.3. Seismic peak ground acceleration of this region is 0.10g, and seismic fortification intensity is 7 degrees, the site is Class I ~ II.. Warehouse 1# is in an area helping anti-earthquake and other buildings are in the areas adverse to anti-earthquake. Saturated silty sands are only sparsely discovered in the layers shallower than 20m within this site and so there is no possibility of foundation soil earthquake liquefaction within the site.4. Groundwater level in the prospecting boreholes measured during this investigation is phreatic level in shallow soil layers and burial depth of measured stable water level is between 0.2~1.4m.As seasons and climates change, groundwater level of 0.5m over the year long can be observed during design.5. There are no pollution sources or pollution history around the site of proposed project. According to the analysis on the groundwater and surface water samples obtained from the project completed by our institute near this site, water corrosiveness was determined according to relevant specifications, and it is determined that groundwater within the site has no corrosive action on concrete and rebars in concrete and has weak corrosive action on steel structures, and the soil has no corrosive action on building materials.6. No hidden creek or ponds are found during the investigation. But this site is a composition of soil and rock, so differential settlement and pile end sliding along rock surface will possibly occur if there is any negligence or omission, to which great attention should be paid during design of construction drawings. Besides, proper gradient of artificial slope in the south of the site should be determined due to a large quantity of excavation work and slope stability should be ensured.7. According to the investigation, no underground barriers seriously affecting the project construction are discovered. However, there is made ground layer of quite thickness on the surficial part, which is mainly composed of broken block stones, with loose construction. Please pay attention to that during construction.5.2 Recommendations1. According to engineering geological conditions of the site, it is recommended that light buildings such as office building and gate guard house can be built on natural foundation, with silty clay of Layer ② used as bearing stratum for natural foundation. Water pond area and other low areas can be treated using soil replacement cushion method.2. Warehouses should apply different forms of foundations depending on different topographical units where they are. In original low-hill area, it is recommended to use natural foundation as the foundations of buildings there, with highly-weathered bedrock or moderately-weathered bedrock used as foundation bearing stratum. In plain area, pile foundation is recommended, in order to reduce differential settlement of the foundations and ensure that it is limited to the range specified by the specifications. If load on a single pile is not great, cast-in-place pile with driven casing can be used, with Layer ⑥ or completely-weathered bedrock of Layer ⑦1 used as bearing stratum for pile end and pile end driven into bearing stratum by 3×pile diameter or more. If cast-in-place pile with driven casing cannot meet the requirements for bearing capacity, Φ600or larger borehole cast-in-place concrete pile embedded in the rock can be used, with highly-weathered bedrock of Layer ⑦2 or moderately-weathered bedrock of Layer ⑦3 used as。