外文资料翻译---柔弱岩石上短距离隧道的动态施工力学的研究

毕业设计外文资料翻译
题目柔弱岩石上短距离隧道
的动态施工力学的研究
学院土木建筑学院
专业土木工程
班级土木
学生
二〇一一年三月四日
Modern Applied Science V ol. 4, No. 6; June 2010 柔弱岩石上短距离隧道的动态施工力学的研究
吴恒斌(通讯作者)
重庆长江三峡大学土木工程系
中国重庆万州市二段沙龙路780号
电子邮件:hbw8456@
贺云翔
重庆长江三峡大学土木工程系
中国重庆万州市二段沙龙路780号
郭良松
聊城建宇工程有限公司
中国聊城252000
摘要
基于建设理论的新奥地利方法((NAM)),依赖在柔弱岩石的短距离隧道工程,通过构建数学模型并进行了三维弹塑性有限元法的建构过程中,双边墙的施工方法。

分析隧道周围一些测量点位移的变化和隧道开挖和洞室群围岩的稳定性,通过分析地表塌陷、承担的力量支护结构与塑性区。

结果表明,上述构造法是合理的在以后的隧道开挖，地表沉陷，隧道变形与早期隧道开挖的影响比较明显。

关键词:柔弱的岩石、小距离隧道、动态建筑机械、数值模拟
1介绍
过程的开挖与支护隧道是一项复杂的机械加工过程，施工过程之间的差别，开挖顺序，支持的时间大为影响工程结构系统(SHE et al., 2006).的力学效应由于周围岩石条件的复杂性普通的类似项目在柔弱岩石特别是小距离隧道工程的复杂连接中是不够的，因此,根据在施工过程中各负荷情况，在不同的围岩中有必要进行机械模拟和分析在柔弱岩石隧道衬砌方面的研究，SUN et al. (1994)考虑了时空效应隧道挖掘表面建立三维数模型。

CHENG et al. (1997) 分析了力学机制和FLAC隧道衬里复杂的承载能力，得到一些有用的结论。

JIN et al. (1996) 应用非线性粘弹性理论进行了三维有限元模拟圆隧道开挖过程。

Karakus(2007)阐述了由平面应变分析造成的三个尺寸挖掘影响。

因为时空效应还不能全部体现,许多研究人员进行了三维弹塑性有限元法和隧道开挖的弹塑性分析(AN, 1994, XIAO, 2000 & ZHU et al. 1996)。

在小距离隧道方面的研究LIU et al. (2000)在中国第一个超级短距离隧道进行的测试中距离隧道在中国。

WAN et al. (2000) 取得了具体小距离隧道的概念。

JIN et al. (2004) 通过数值模拟分析讨论了施工方法的适应性。

YAN et al.分析了在不同施工
方案中支撑的机械特性和变形规则。

LIU et al。

(2006)介绍了短
距离8车道公路隧道的设计方案。

大多数上述研究的目的分别是柔弱岩石隧道的建筑特征和小距离隧道建设方案的比较和选择由于很少做结合两方面的讨论，因此，有必要研究小距离柔弱岩石动态施工特点。

2工程概况
2.1工程地质
地质调查显示,底部隧道主要打通的是下面的基础，主要是泥岩，砂岩。

撞击地层的方向交叉降至85°。

隧道、地层倾角约有9°,结合层岩石很普通，岩石的等级是五级。

地下水很匮乏，隧道中水的主要形式是潮湿或滴下来。

钢筋混凝土的极限抗压强度= 4.59Mpa，完整性因素KV=0.65,K1 = 0.2,K2 = 0.3,K3 = 0,[工程量清单计价]= 219。

砂岩钢筋混凝土的极限抗压强度=2549Mpa,完整因素KV=0.64,K1= 0.5,K2 = 0.2,K3 = 0,[工程量清单计价]= 319。

地质构造的表面非常发达，岩体极其支离破碎,而且块强度不够强。

所以它属于典型的类柔弱的岩石。

2.2工程施工方法。

双墙指导施工方法中的配角,以先进的小管为了减少隧道施工对高速公路经营管理的影响，确保隧道建设的安全双边墙施工方法以先进的小管作为支撑角色引导。

先进小管的外半径是Φ42mm,长度是四十厘米。

在施工过程中,开挖的长度是受到严格控制的，主要支撑每隔四米设置一个。

30厘米厚的封闭钢筋混凝土环被襄铸在第二内衬和主要支撑之间。

螺栓的形式是空心注浆和quincunx布局、直径和长度是作为轨道后,4.5米、垂直和周向所在分别是200厘米和80厘米第二内衬和主要支撑被浇铸成28厘米厚C20模型和60厘米厚C25厚钢筋混凝土模型
3数值模型
隧道长度是选为仿真模型,该模型被选为20米长，该模型有21850个小构件其中螺栓有3850构件(图1)。

隧道围岩被认为是弹塑性材料。

因为支撑结构的力学性能优于围岩,所以它可以被看作是弹性材料。

钢拱的影响在架子上和先进的小管喷射混凝土可以模拟使用等效的方法。

Tab.1是基本力学参数的物质。

为确保计算的准确性该模型维度可以设为:左和右都长50米垂直于地球表面下为50米。

4进行结果分析
4.1分析地表沉陷,
地面沉降应严格控制,以确保隧道施工中高速公路运营管理的安全隧道施工。

从图2,图像的地表沉陷隧道开挖完成后,它可以看出地表沉陷对称分布近似在双线隧道、展示W的形状。

早期隧道拱顶端地面沉降规模最大，沉降值为5.31mm，这是由于早期隧道开挖完成以后，后期隧道建设造成的扰动，这和现场监测的信息和数据规
则是一致的。

后期隧道拱顶端地面沉降量是5.31mm。

在隧道中轴线附近的地表沉降小于两个隧道拱顶所在的地表沉降，沉降值只有2.87mm。

可以从图二中得出的结论是隧道开挖的影响对地表沉陷趋于稳定的距离范围是中轴线直径的3.5倍,也揭示了该仿真模型的选择范围是没有错误的
4.2巷道变形分析
如图3所示,后期隧道拱顶端的垂直地表沉降是7.20mm,最大的垂直地表沉降值出现在早期隧道拱顶端。

因为之后的隧道施工效,是7.33mm。

与一般的大垮较浅深度的隧道地表沉降的现场测量值相比，顶部处理的沉降值略小。

可以假定,先进的小管在加固岩石上发挥了很大作用，逆变值相对较大，早期的隧道和后期的隧道分别是9.87mm 9.85mm。

分析结果表明,隧道围岩的垂直缺陷值满足施工的需要、初始参数设定隧道结构是合理的。

4.3支撑承载力的分析
如图4所示,出现在拱脚的最大受力值是7.31Mpa.。

在施工过程中应该加强现场监测的力度。

从图五中以发现在拱顶和拱脚位置的螺栓的轴向力更大。

最大值是42.56kN，满足抗拉强度要求。

螺栓轴向力最主要的分布形式是“凸肚”式。

符合螺栓轴向力在柔弱岩石上的分布格局。

处在拱脚位置的少量螺栓时处于压缩状态的。

可能由于主要支撑的刚度太大，结果是减少了拱脚的变形和反演胀的现象。

从图六中可以看出第二内衬的应力规律和主要支撑是相似的，边墙的压力要大于其他部位最大应力值是0.2Mpa满足在中国要求的标准
4.4塑性区分析
从图7,便会发现,塑性区主要分布在拱顶、拱门、拱门脚的位置，这也许是由于由双边墙施工方法造成的过多的应力进入了侧墙。

先进的小管的支持、初期支护,其次内衬可以预防塑性区进一步扩张,塑性区深度,不会超过一半的隧道宽度,而在允许范围内。

所以隧道围岩塑性区的发隧洞的稳定性隧道仍然情况稳定。

5结论
隧道地表沉陷的分布在中心轴线基础上,显示W型,由于解决方案主要集中在3.5倍中心轴线的直径范围内，先进小管的支持能够加固围岩有效防止两个隧道之间塑性区的扩张。

从围岩结构的变形结果可以看到后期隧道开挖地表沉陷与隧道变形对早期的隧道的影响大于早期隧道开挖对后期隧道的影响。

对上述结果进行分析地面沉降、隧道周边的垂直位移，支撑的承载力和塑性区双边墙建设方案是合理的。

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图1 有限元分析模型
图2 地表沉陷图表图3 围岩的垂直位移（mm）
图4 主要支撑的等量压力图5 螺栓的轴力图
图6 次连接的等量应力图7 围岩的塑性区Study on Dynamic Construction Mechanics of Small-Distance Tunnel
in Soft and Weak Rocks
Hengbin Wu (Corresponding author)
Department of Civil Engineering, Chongqing Three Gorge University
780 Erduan Shalong Road, Wanzhou District, Chongqing 404000, China
E-mail: hbw8456@
Yunxiang He
Department of Civil Engineering, Chongqing Three Gorge University
780 Erduan Shalong Road, Wanzhou District, Chongqing 404000, China
Guoliang Song
Liaocheng Jianyu Construction Engineering Co.,Ltd
Liaocheng 252000, China
Abstract
Based on the construction theory of New Austria Method(NAM), relyed on a tunnel project of small distance in
soft and weak rocks, this paper builds the numerical model and simulates 3D finite element method elastoplastic
of the construction process by the construction method of double-sidewalls. The displacement changes of some
points around the tun nel are analysised with the tunnel’s excavation. The safety of the tunnel structure and stability of surrounding rock are estimated by analyzing the surface subsidence, forces undertaken by the supporting structures and plastic zone. The results show that the method of construction mentioned above is reasonable, the influence of the later tunnel excavation on the surface subsidence and tunnel deformations of the
earlier tunnel excavation is relatively obvious.
Keywords: Soft and weak rocks, Small distance tunnel, Dynamic construction mechanics, Numerical simulation
1. Introduction
The excavation and supporting process of tunnel is a complicated mechanical process, the differences of construction process, excavation sequence and supporting time greatly influence on the mechanics effects of engineering structure systematic(SHE et al., 2006). Because of the complexity of the condition of surrounding
rock, the ordinary analogy of projects is not enough in the complex lining in soft and weak rocks especially in
th e tunnel engineering with small distance, so it’s necessary to conduct the mechanical simulating and analyzing
in different surrounding rock characters according to the different forcing stages in each load case during construction processes.
In the aspect of the research on the tunnel lining in soft and weak rocks, SUN et al. (1994) builded the three dimension model considering the time-space effect of tunnel excavating surface. CHENG et al. (1997) analyzed
the mechanical mechanism and carrying capacity of complex lining for tunnels with FLAC, and got some useful
conclusions. JIN et al. (1996) conducted three dimension FEM (finite element method) numerical simulation to
the excavation processes of circle tunnel using the nonlinear viscoelastic theory. Karakus(2007)elaborated three
dimension excavating effect caused by plane strain analyses. Because the time-space effect could not be fully reflected, many researchers conducted three dimension FEM elastoplastic and visco-elastoplastic analyses to tunnel excavation(AN, 1994, XIAO, 2000 & ZHU et al., 1996).In the aspect of the research in the tunnel of small distance, LIU et al. (2000) carried out the tests on Zhaobaoshan tunnel, which is the first super small distance tunnel in China. WAN et al. (2000) made specifically the concept of small distance tunnel. JIN et al. (2004) discussed the adaptability of the construction methods through the numerical simulating. YAN et al. (2006) analyzed the mechanical characteristic and deformation rules of the supports in different construction methods. LIU et al. (2006) introduced the design scheme of highway tunnel of small distance with 8 lanes. Most
of studies mentioned above were aimed separately at construction characters of the tunnel in soft and weak
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and the comparison and selection of the construction schemes of small distance tunnel. The discussion combining the two aspects is less made, so it’s necessary to study the dynamic construction mechinics characteristic of small distance tunnel in soft and weak rocks.
2. Engineering General Situation
2.1 Engineering Geology
The geological survey shows that the bottom, the tunnel mostly get through, is the Jurassic upper Shaximiao, and
the underlying bedrock is the interbedded of mudstone and sandstone. The strike direction of the strata intersect
the tunnel axis to 85°, the strata dip angle is about 9°, the combination between the layers of rock is general, and
the level of rock is grade V. The groundwater is poor, and the main form of the water in tunnel is damp or dripping. The saturated uniaxial compressive strength of mudstone Rc=4.59Mpa, Integrity factor Kv=0.65, K1=0.2, K2=0.3, K3=0, [BQ]=219. The saturated uniaxial compressive strength of Sandstone Rc=25.49Mpa, integrity factor Kv=0.64, K1=0.5, K2=0.2, K3=0, [BQ]=319. The surface of geological structure is very developed, the rock body is extremely fragmented, and the block strength is not strong. So it belongs to the typical category of the soft and weak rocks.
2.2 Engineering Construction Method
The double side-walls construction method is guided under the supporting role with advanced small pipe, in order to reduce the influence of tunnel construction on the highway operations, ensure the safety of tunnel construction. The outside radius of advanced small pipe is Φ42mm, the length is 3.5m and the circumferential
spacing is 40cm. In the construction process, the excavation length is controlled strictly, the primary support is
constructed every 4m, and the 30cm thick closed loop of steel concrete is molded between the secondly lining
and primary support. The bolts are the forms of hollow grouting and quincunx layout, the diameter and length
are setted as 25mm and 4.5m, the vertical and circumferential spacing are located 200cm and 80cm apart. The
primary support and secondly lining are forms of the 28cm thick C20 shotcrete and 60cm thick C25 model reinforced concrete.
3. NumericalModel
The tunnel length in simulating model is selected as 20m, and the model has 21850 elements, in which bolts have 3850 elements(Fig.1). The tunnel surrounding rock is considered to be elastoplastic material. Because the
mechanics characteristic of the support structure is better than the surrounding rock, so it could be regarded as
elastic material. The effect of steel arch shelf in shotcrete and advanced small pipe could be simulated using equivalent method. Tab.1 is the basic mechanics parameter of the material. In order to ensure the veracity of calculation, the model dimension can be set as : left and right are all 50m, vertical to earth surface, down is
4 Results Analysis
4.1 Surface Subsidence Analysis
The surface subsidence should be strictly controlled, in order to ensure the safety of highway operations in the
tunnel construction. From Fig.2, the graph of the surface subsidence after completion of the tunnel excavation, it
can be seen that the surface subsidence is approximate symmetrical distribution on the two-lane tunnel, showing
W shape. the surface subsidence in the top of the earlier tunnel vault is largest, the value is 5.31mm, which is due
to the construction disturbance caused by the later tunnel after completion of the earlier tunnel excavation. This
is consistent with the information and data rules of on-site monitoring. The surface subsidence in the top of the
later tunnel vault is 5.31mm, the surface subsidence near the central axis line are smaller than the top of the two
tunnel vaults, the value is only 2.87mm. Generally speaking, the surface subsidence can guarantee normal construction under the safety operation of highway. The conclusion, which could also be seen from Fig.2, is that
the impact of the tunnel excavation on surface subsidence tends to be stable in the range of the distances of 3.5
times the diameter to the central axis, which also indicates the selection range of this simulation model is within
the error.
4.2 Tunnel Deformation Analysis
As can be seen from Fig.3, the vertical subsidence of the later tunnel vault is 7.20mm, and the largest value of
the vertical subsidence, which appears in the earlier tunnel vault because of the construction effect of the later tunnel, is 7.33mm. The value of crown settlement is slightly small compared with the on-site monitoring value of
the tunnels with general shallow-depth and large-span. It can be assumed that, the advanced small pipe has played effectively a role of reinforcing rock. The invert heaving value is relatively large, the earlier tunnel and
later tunnel are 9.87mm, 9.85mm. The analysis indicates that the vertical deformation of the tunnel surrounding
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Modern Applied Science Vol. 4, No. 6; June 2010
rock meets the construction requirement, the initial parameters set of the tunnel structures are reasonable. 4.3 Analysis of Forces Undertaken by Supports
As can be seen from Fig.4, the largest value which appears in the arch foot is 7.31Mpa. The on-site monitoring in
the arch foot should be strengthened in the construction process. From Fig.5, it can be found that, the axial force
of bolts is larger in the position of the vault and hance, the largest value is 42.56kN, which meets the requirement
of the tensile strength. The most distribution of the bolts axial force is the form of “convex belly”, which is consistent with the distribution pattern of the bolt axial force in soft and weak rocks. A small amount of bolts in
arch foot position are compression state, which maybe due to the stiffness of the primary support is too large, resulting in less deformation of arch foot and the phenomenon of invert heaving. As can be seen from Fig.6, the
stress law of the secondly lining is similar with primary support. The side-wall stress is larger than the others, the
largest value is 0.2Mpa, which meets the requirement criterion in China.
4.4 Plastic Zone Analysis
From Fig.7, it can be seen that, the plastic zone is mainly distributed in the position of the vault, arch and arch
foot, which is probably due to the side-walls undertaken excessive forces caused by double-sidewalls construction method. The supports of advanced small pipe, primary support and secondly lining can prevent effectively the further expansion of the plastic zone, the depth of plastic zone does not exceed the half of the tunnel width, which is within the allowable range. Therefore the development of plastic zone of the tunnel does
not affect significantly the stability of the tunnel, and the tunnel is still in stable condition.
5. Conclusions
The distribution of the tunnel surface subsidence is on the central axis basis, showing W shape, and the settlement mainly concentrated in the range of the distance of 3.5 times the diameter to the central axis. The support of advanced small pipe can reinforce the surrounding rock, and prevent effectively the expansion of the
plastic zone between the two tunnels. From the deformation results of the surrounding rock, it can seen that, the
influence of the later tunnel excavation on the surface subsidence and tunnel deformations of the earlier tunnel
excavation is larger than the earlier tunnel impacts on the later tunnel. From the results analysis mentioned above
of the surface subsidence, vertical displacement of the tunnel surrounding, undertaken forces of the supports and
the plastic zone, the construction schemes of double- sidewalls is reasonable.
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Figure 1. The Finite Element Analyssis Model
Table 1. Baasic mechanicaal parameters oof surroundingg rock and tunnnel structures
Figure 2. The Graph of Surface Subbsidence
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Moderrn Applied Sciience Vool. 4, No. 6; Junne 2010
Figure 3. Thhe Vertical Dissplacement of tthe Surroundinng Rock(mm)
Figure 4. The Equivallent Stress of he Primary Suupport(pa)
Figure 5. Thee Axial Force oof the Bolts(N))
Figure 6. The Equivallent Stress of he Secondly Lining(pa) Figuure 7.The Plasttic Zone of thee Surrounding Rock
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