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1.
Pierpaolo Oreste Giovanni Spagnoli Cesar Alejandro Luna Ramos Lisa Sebille 《Geotechnical and Geological Engineering》2018,36(4):2143-2169
Hyperstatic Reaction Method considers the interaction between the shotcrete lining and the rock mass modelling half tunnel section by beam elements connected by nodes, which can develop bending moments, axial forces and shear forces. The interaction between ground and support is represented by Winkler type springs in the nodes of the numerical model, in the normal and tangential direction. 1944 analyses were developed considering three different tunnel radius values (2.0, 4.5 and 7.0 m), three different rock types (RMR = 40, RMR = 60 and RMR = 80), three different stress ratios acting on the linings (\(K = 1, \,K = 0.5\) and \(K = 0\)), three different lining thickness values (0.1, 0.2 and 0.3 m) and three values of the average elastic modulus of the shotcrete (6000, 9000 and 12,000 MPa). Besides, also two different stiffness values of the tangential springs at nodes were considered. Results show that the lining thickness and the elastic modulus of the shotcrete have a strong influence on the bending moment values which develop inside. The maximum axial force is not practically influenced by the lining elastic modulus and thickness. Both maximum bending moments and maximum axial forces increase in a linear way with the vertical load value; tunnel radius, \(K\) and RMR values of the rock mass have also a great influence on the maximum bending moment and axial force. Besides, it is possible to note how the absence of shear interaction between the lining and the rock mass causes bending moment values in the lining higher with respect to the case where the stiffness of the tangential springs at nodes equals to half the stiffness of the normal springs. For this reason, the neglectance of the shear interaction between the lining and the tunnel wall leads to an overdesign of the SC lining. 相似文献
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This paper proposes a numerical approach to the hyperstatic reaction method (HRM) for the analysis of segmental tunnel linings. The influence of segmental joints has been considered directly using a fixity ratio that is determined on the basis of the rotational stiffness. The parameters necessary for the calculation are presented. A specific implementation has been developed using a FEM framework. This code is able to consider the three‐dimensional (3D) effect of segment joints in successive rings on the tunnel lining behaviour. The present HRM allows one to take an arbitrary distribution of segment joints along the tunnel boundary into consideration. In addition, the rotational stiffness of segment joints has been simulated using nonlinear behaviour, as it is closer to the true behaviour of a joint than linear or bilinear behaviour. The numerical results of three hypotheses on ring interaction, which allow the 3D effect of a segmental tunnel lining to be taken into account, have been compared with data obtained from the shield‐driven tunnel of the Bologna–Florence high‐speed railway line project. The numerical results presented in the paper show that the proposed HRM can be used to effectively estimate the behaviour of a segmental tunnel lining. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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针对某核电取水隧洞工程,采用非线性的动力分析方法,用Flac3D建立大型三维有限差分模型,模拟隧洞洞口段在场址时程地震波作用下的地震响应规律,同时通过建立隧洞洞口处回填高边坡的二维有限元模型,进行洞口边坡在地震动作用下的稳定性分析,得出其边坡滑动面位置和动力安全系数时程曲线。通过场址地震波的输入,探讨隧洞洞口及边坡的结构响应特点,得出隧洞洞口衬砌内力随地震波作用的时程变化曲线,绘制隧洞衬砌内力图,同时给出隧洞洞口段高边坡安全系数。分析结果表明,隧洞洞口抗震的薄弱部位位于隧洞拱肩及边墙位置。分析方法及结论对于隧洞的抗震设计具有一定的参考价值。 相似文献
4.
This paper presents a novel approach to the simulation of NATM tunnel construction using the Boundary Element Method (BEM) as principal numerical method. This new approach has the advantage that only the excavation surface, the possible plastic zones and the tunnel lining have to be discretised. The whole rock mass is represented by the BEM whereas the Finite Element Method (FEM) is used to represent the tunnel lining only. Thus, a general coupling strategy for coupling three-dimensional boundary elements with shell finite elements (shotcrete) and beam finite elements (steel arches) is presented. To achieve realistic results the effect of hydration of the shotcrete and yielding of the steel arches is considered in the excavation process. Furthermore, the nonlinear rock behaviour is modelled more realistically by using a powerful hierarchical constitutive model which considers a large range of rock materials. The combination of these ideas results in higher user-friendliness and efficiency. Some verification tests and practical applications in tunnelling are presented. 相似文献
5.
Practical Estimate of Deformations and Stress Relief Factors for Deep Tunnels Supported by Shotcrete 总被引：1，自引：1，他引：1
Summary. Even though ground-support interaction in the vicinity of the tunnel face is a typical 3D problem, tunnel support design is
usually based on simplified plane strain models, which are strongly dependent on the assumed degree of ground stress relief
at the time of lining installation. The paper focuses on tunnels supported by shotcrete close to the face, where the interaction
between the loading process and progressive hardening of the green shotcrete makes the problem time-dependent. A constitutive
law characterized by the time-dependent stiffness and strength of the shotcrete is employed herein. The results of an extensive
parametric study based on 3D axisymmetric models are presented in the form of non-dimensional design charts, which can provide
guidance to a preliminary evaluation of convergences and support loadings.
Moreover a strategy is proposed to enhance the capability of simplified design methods (2D models, Convergence-Confinement
Method). This consists in a “guided estimate” of stress relief factors, which again is based on the results of 3D time-dependent
analyses. Finally, by way of example, the proposed method is applied to two well-documented case-histories. 相似文献
6.
This paper presents an embedded beam formulation for discretization independent finite element (FE) analyses of interactions between pile foundations or rock anchors and the surrounding soil in geotechnical and tunneling engineering. Piles are represented by means of finite beam elements embedded within FEs for the soil represented by 3D solid elements. The proposed formulation allows consideration of piles and pile groups with arbitrary orientation independently from the FE discretization of the surrounding soil. The interface behavior between piles and the surrounding soil is represented numerically by means of a contact formulation considering skin friction as well as pile tip resistance. The pile–soil interaction along the pile skin is considered by means of a 3D frictional point‐to‐point contact formulation using the integration points of the beam elements and reference points arbitrarily located within the solid elements as control points. The ability of the proposed embedded pile model to represent groups of piles objected to combined axial and shear loading and their interactions with the surrounding soil is demonstrated by selected benchmark examples. The pile model is applied to the numerical simulation of shield driven tunnel construction in the vicinity of an existing building resting upon pile foundation to demonstrate the performance of the proposed model in complex simulation environments. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
7.
求水山隧道下穿机荷高速段新奥法施工有限元计算 总被引：5，自引：0，他引：5
结合求水山隧道的暗挖法施工方案,对软土地区浅埋隧道下穿高速公路的施工过程进行了有限元模拟,以用于评价按该施工方案施工时对其上部高速公路的影响。由于该段隧道最小埋深仅4 m,且上部还有高速公路车辆荷载,因此,在设计时采用了新奥法结合管棚工法的方案。有限元建模使用平面应变单元,通过引入应力释放分析步和使用追踪单元等方法充分体现了新奥法的特点,并通过设置耦合和弹簧的方法实现了管棚工法的模拟,在计算中还考虑了开挖顺序和支护顺序的影响。研究结果表明：对于上部有荷载的浅埋暗挖隧道,控制衬砌的水平向变形能改善衬砌环的工作状态,因此,可显著减少开挖引起的隧道顶面沉降,新奥法结合管棚工法可较好地控制该类型隧道开挖引起的地表沉降变形。 相似文献
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为了能够较快速、较准确地估计出穿越活断层城市地铁隧道的抗震薄弱部位,基于拟静力弹塑性有限元方法,以北京地铁7号线工程的区间隧道作为研究对象,采用数值模拟的方法研究了在走滑断层位错作用下地铁隧道的非线性反应。通过在数值计算模型中嵌入合理的损伤塑性本构模型,利用损伤指标研究了走滑断层下衬砌结构的破坏形式,重点分析了结构损伤的开始部位、发展过程以及最终的损伤程度,并建立了能够估计结构损伤范围及破坏最严重位置的统计关系式。结果表明,在走滑断层作用下衬砌结构出现损伤的区域主要发生在活断层附近一定范围内,拱腰部位的损伤最为严重;增加基岩上覆土层厚度能够减轻衬砌结构的破坏程度,当基岩上覆土层厚度大于等于临界覆盖土层厚度时可以不考虑走滑断层断裂对于浅埋隧道的影响。衬砌结构损伤区域长度与震级的大小和土层厚度有关,损伤最严重的位置随土层厚度的变化而改变。研究成果为穿越活断层地铁隧道的抗震设计和安全性评价提供了参考依据。 相似文献
11.
盾构法施工过程的有限元模拟 总被引：3，自引：0，他引：3
在综合考虑了现有的有限元模拟方法的基础上,对部分仿真模拟细节进行了改进,改进了水平荷载的施加方法,用"等代层"来模拟盾尾建筑空隙,用预设单元的刚度迁移来模拟盾构的推进过程。通过对某地铁隧道盾构施工过程的模拟,分析了盾构推进过程中地表土体的位移与变形,计算得到的隧道横断面和隧道纵向地面沉降分布曲线与实测数据比较接近,结果证明了模拟方法是可行的。 相似文献
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This paper describes finite element procedures that have been developed to model the ground movements that occur when a shallow tunnel is installed in a clay soil. This study is part of a wider project concerned with the development of new methods to predict the likely extent of damage to surface structures caused by nearby shallow tunnelling. This particular paper, however, is concerned only with the numerical model of tunnel installation. The structural liner is an important component of this tunnel installation model; two different ways of modelling the liner (based on continuum elements and shell elements) are discussed in the paper. A test problem consisting of the installation of a lined tunnel in an elastic continuum is used to investigate the merits of these different approaches. When continuum elements are used to model the liner, the numerical results agree well with an analytical solution to the problem. When shell elements are used to model the liner, however, the results were found to be significantly influenced by the particular formulation adopted for the shell elements. Example analyses, involving incremental tunnel construction in a clay soil where the soil is modelled using a kinematic hardening plasticity model, are described. These analyses confirm that a thin layer of continuum elements may be used, satisfactorily, to model tunnel linings in a soil–structure interaction analysis of this sort. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
14.
Pavlos Nomikos Reza Rahmannejad Alexandros Sofianos 《Rock Mechanics and Rock Engineering》2011,44(5):553-564
An exact closed form solution is derived for the mechanical behaviour of a linear viscoelastic Burgers rock around an axisymmetric tunnel, supported by a linear elastic ring. Analytical formulae are provided for the displacement of the rock/lining interface and for the pressure exerted by the rock on the lining, taking into account the stiffness and its installation time. Results calculated from these formulae do validate the corresponding numerical results of a 2D finite differences code. Further, comparison to previous existing solutions for the same viscoelastic model indicates similarities and differences. A parametric study is performed to investigate the effect of the viscoelastic constants, the stiffness and installation time of the support. The derived closed form solution is used to construct the time-dependent Supported Ground Reaction Curves of the viscoelastic rock, i.e. the time contour plots on the convergence confinement diagram. The importance of the effect of the support on the restrained rock creep and the exerted pressure on the lining, during the design life of a structure, is examined. 相似文献
15.
This paper presents a numerical formulation of a three dimensional embedded beam element for the modeling of piles, which incorporates an explicit interaction surface between soil and pile. The formulation is herein implemented for lateral loading of piles but is able to represent soil–pile interaction phenomena in a general manner for different types of loading conditions or ground movements. The model assumes perfect adherence between beam and soil along the interaction surface. The paper presents a comparison of the results obtained by means of the present formulation and by means of a previously formulated embedded pile element without interaction surface, as well as reference semi‐analytical solutions and a fully 3D finite element (FE) model. It is seen that the proposed embedded element provides a better convergence behavior than a previously formulated embedded element and is able to reproduce key features of a full 3D FE model. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
16.
Ali Nemati Hayati Mohammad Mehdi Ahmadi Mahdi Hajjar Aliakbar Kashighandi 《国际地质力学数值与分析法杂志》2013,37(14):2170-2185
Tunnels constructed using New Austrian Tunnelling Method (NATM) are always based on certain round (unsupported) advance lengths, after which, the temporary lining is placed. The settlement of the ground surface resulting from such construction is of high significance in design and practice. The existing data in this respect, however, is scarce. It is the aim of this paper to propose a semi‐analytical procedure based on three‐dimensional finite element analyses to predict the maximum surface settlement of the ground in NATM tunnels under different combinations of tunnel diameter, overburden depth, round length and soil and lining properties. The comparison of the results with three case histories of real tunnels reveals reasonable accuracy of the present solution. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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金华山软岩铁路隧道施工过程围岩屈服接近度分析 总被引：1，自引：0，他引：1
隧道施工过程中围岩处于复杂应力状态下,隧道围岩屈服区演化特征的确定对于围岩稳定性分析和开挖支护方案优化具有重要的意义。采用屈服接近度指标衡量围岩破坏接近程度可以合理地描述复杂应力状态下围岩的应力危险性,对Mohr-Coulomb类岩体材料的屈服接近度函数进行了相应的推导,并在非线性有限元用户子程序上编程予以实现。介绍了赣州-龙岩铁路DKl33+095～DKl38+237段软弱围岩单线隧道正台阶步施工方案以及湿喷纤维混凝土支护方案。为了对该隧道施工过程中隧道围岩屈服区的演化特征进行合理评价,采用非线性有限元法对软弱围岩条件下的铁路隧道施工过程进行了数值模拟,分析了施工过程中隧道围岩屈服接近度分布特征,判定了隧道台阶步施工过程中隧道围岩的稳定性。分析结果表明:该隧道施工过程中围岩破坏区主要发生在下台阶步施工过程中;屈服接近度指标比传统的塑性区分布提供的信息更加丰富,有利于工程技术人员定量地评价隧道开挖支护方案。 相似文献
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土-地下结构体系地震反应的简化分析方法 总被引：1，自引：0，他引：1
基于Penzien提出的土-结构动力相互作用分析的集中质量模型,考虑等价土体的层间剪切刚度与阻尼效应,提出了土-地下结构动力相互作用体系地震反应分析的简化分析方法,选取具有不同地震动特性的Taft波、汶川地震什邡八角波和松潘波作为基岩水平向输入地震动,采用该简化方法和二维有限元法对土-地铁地下车站结构体系的地震加速度反应特性进行了对比分析,结果表明：简化方法计算的地铁地下车站结构峰值加速度反应大于二维有限元法计算的地铁地下车站结构峰值加速度反应,两者的差异与输入地震动特性有关,但其随地铁地下车站结构高度变化的总体趋势较为一致;随着输入地震动强度的增大,其差异程度也有所加大。该简化方法可合理反映土-地下结构体系的动力相互作用效应,可作为地下结构抗震设计分析的一种辅助方法。 相似文献
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《Computers and Geotechnics》2006,33(4-5):234-247
For shield-driven tunnels, the influence of the soil and grout material properties and of the cover depth on the surface settlements, the loading and deformation of the tunnel lining and the steering of the TBM is investigated numerically. To this end, comparative numerical simulations of a mechanised tunnel advance in homogeneous, overconsolidated, soft, cohesive soil below the ground water table are performed and sensitivities are evaluated. The advancement of the step-by-step tunnel construction process is modelled using a three-dimensional finite element model, which takes into account all relevant components of shield tunnelling. The material behaviour of the saturated soil and the tail void grout is modelled by a two-field finite element formulation in conjunction with an elasto-plastic Cam-Clay model for the soil and a hydration-dependent constitutive model for the grout. The analyses provide valuable information with regard to the significance of the investigated parameters and demonstrate the complexity of the various interactions in shield tunnelling. 相似文献