水平及竖向地震共同作用下双线隧道的响应分析     

王杰  刘华北  邹炎  阮滨 《震灾防御技术》2020,15(4):670-683

基于有效的土-结相互作用有限元数值模拟方法,利用有限元软件ABAQUS对水平及竖向地震共同作用下双线盾构隧道的地震响应进行分析研究。地震动输入选取近场地震Loma、ChiChi、Mammoth和WoLong的基岩水平及竖向加速度时程记录。结果表明,不同近场地震记录对隧道结构的作用不同,隧道的地震反应与场地性质及地震动的频谱特性密切相关。对比隧道在水平及竖向地震动共同作用下的响应与单向水平地震动作用下的响应,发现隧道的最大地震附加内力及其分布均发生较大的变化,在隧道结构抗震设计中需引起重视。另外,分析中还考虑了在双向地震动共同作用下,隧道间距、土-结接触面的摩擦系数、土-结相对刚度、输入的地震记录和竖向地震动相对强度对隧道地震响应的影响等,研究结果对隧道工程的抗震设计具有一定的参考价值。  相似文献   

A finite strain solution for the elastoplastic ground response curve in tunnelling: rocks with non‐linear failure envelopes          下载免费PDF全文

Apostolos Vrakas 《国际地质力学数值与分析法杂志》2017,41(7):1077-1090

This paper generalizes the finite strain Coulomb solution of Vrakas and Anagnostou (Int J Numer Anal Meth Geomech 2014; 38(11): 1131–1148) for the classic tunnel mechanics problem of the ground response curve to elastoplastic grounds satisfying a non‐linear Mohr's failure criterion. A linear (Coulomb‐type) plastic potential function is used, leading to a non‐associated flow law, and edge plastic flow is considered in the plastic zone. The solution for a general non‐linear Mohr's failure criterion is semi‐analytical in that it requires the evaluation of definite integrals. In the special case of the Hoek–Brown criterion, however, these integrals are calculated analytically, resulting in a rigorous closed‐form series solution. The applicability of the derived solution is illustrated through the example of the Yacambú‐Quibor tunnel, where very large deformations were observed when crossing of weak graphitic phyllites. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Making the Subterranean Visible: Security,Tunnels, and the United States–Mexico Border     

Cynthia Sorrensen 《Geographical review》2014,104(3):328-345

The number of unauthorized tunnels discovered through the U.S.–Mexico border has risen dramatically since the mid‐1990s. These tunnels are problematic for the state because the subterranean border is both less visible and more difficult to monitor and control than is the surface border. In this era of heighten security, the debate on secure borders has intensified. As a result, the need to demonstrate security success at both the national and the agency level has risen. Efforts to make tunnel discoveries (and security) visible are made within border‐security agencies and within national discourse and legislation. These efforts spatially fix tunnels to the border in ways that obscure fuller a understanding of drug trafficking in general. This paper employs archival research, content analysis, and informal interviews with security‐enforcement agents to consider the material presence of tunnels within border landscapes.  相似文献   

Diffraction of anti-plane SH waves by a semi-circular cylindrical hill with an inside concentric semi-circular tunnel   总被引：8，自引：3，他引：5  

Vincent W.Lee  罗昊  梁建文 《地震工程与工程振动(英文版)》2004,3(2):249-262

A closed-form analytic solution of two-dimensional scattering and diffraction of plane SH waves by a semicylindrical hill with a semi-cylindrical concentric tunnel inside an elastic half-space is presented using the cylindrical wave functions expansion method. The solution is reduced to solving a set of infinite linear algebraic equations. Fourier expansion theorem with the form of complex exponential function and cosine function is used. Numerical solutions are obtained by truncation of the infinite equations. The accuracy of the presented numerical results is carefully verified.  相似文献   

A finite strain closed‐form solution for the elastoplastic ground response curve in tunnelling     

Apostolos Vrakas  Georgios Anagnostou 《国际地质力学数值与分析法杂志》2014,38(11):1131-1148

The ground response to tunnel excavation is usually described in terms of the characteristic line of the ground (also called ‘ground response curve’, GRC), which relates the support pressure to the displacement of the tunnel wall. Under heavily squeezing conditions, very large convergences may take place, sometimes exceeding 10–20% of the excavated tunnel radius, whereas most of the existing formulations for the GRC are based on the infinitesimal deformation theory. This paper presents an exact closed‐form analytical solution for the ground response around cylindrical and spherical openings unloaded from isotropic and uniform stress states, incorporating finite deformations and linearly elastic‐perfectly plastic rock behaviour obeying the Mohr–Coulomb failure criterion with a non‐associated flow rule. Additionally, the influence of out‐of‐plane stress in the case of cylindrical cavities under plane‐strain conditions is examined. The solution is presented in the form of dimensionless design charts covering the practically relevant parameter range. Finally, an application example is included with reference to a section of the Gotthard Base tunnel crossing heavily squeezing ground. The expressions derived can be used for preliminary convergence assessments and as valuable benchmarks for finite strain numerical analyses. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

A new closed‐form solution for analysis of unlined pressure tunnels under seepage forces     

Ahamad Fahimifar  Mohammad Reza Zareifard 《国际地质力学数值与分析法杂志》2013,37(11):1591-1613

In this study, a simplified analytical closed‐form solution, considering plane strain and axial symmetry conditions, for analysis of a circular pressure tunnel excavated underwater table, is developed. The method accounts for the seepage forces with the steady‐state flow and is based on the generalized effective stress law. To examine the effect of pore pressure variations and also the boundary conditions at the ground surface, the formulations are derived for different directions around the tunnel. The proposed method can be applied for analysis and design of pressure tunnels. Illustrative examples are given to demonstrate the performance of the proposed solution and also to examine the effect of seepage forces on the stability of tunnels. The simplified analytical solution derived in this study is compared with numerical analyses. It is concluded that the classic solutions (Lame's thick‐walled solution), considering the internal pressure as a mechanical load applied to the tunnel surface, are not applicable to pervious media and can result in an unsafe design. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Numerical Analyses of the Influence of Blast-Induced Damaged Rock Around Shallow Tunnels in Brittle Rock   总被引：2，自引：1，他引：1  

David Saiang  Erling Nordlund 《Rock Mechanics and Rock Engineering》2009,42(3):421-448

Most of the railway tunnels in Sweden are shallow-seated (<20 m of rock cover) and are located in hard brittle rock masses. The majority of these tunnels are excavated by drilling and blasting, which, consequently, result in the development of a blast-induced damaged zone around the tunnel boundary. Theoretically, the presence of this zone, with its reduced strength and stiffness, will affect the overall performance of the tunnel, as well as its construction and maintenance. The Swedish Railroad Administration, therefore, uses a set of guidelines based on peak particle velocity models and perimeter blasting to regulate the extent of damage due to blasting. However, the real effects of the damage caused by blasting around a shallow tunnel and their criticality to the overall performance of the tunnel are yet to be quantified and, therefore, remain the subject of research and investigation. This paper presents a numerical parametric study of blast-induced damage in rock. By varying the strength and stiffness of the blast-induced damaged zone and other relevant parameters, the near-field rock mass response was evaluated in terms of the effects on induced boundary stresses and ground deformation. The continuum method of numerical analysis was used. The input parameters, particularly those relating to strength and stiffness, were estimated using a systematic approach related to the fact that, at shallow depths, the stress and geologic conditions may be highly anisotropic. Due to the lack of data on the post-failure characteristics of the rock mass, the traditional Mohr–Coulomb yield criterion was assumed and used. The results clearly indicate that, as expected, the presence of the blast-induced damage zone does affect the behaviour of the boundary stresses and ground deformation. Potential failure types occurring around the tunnel boundary and their mechanisms have also been identified.  相似文献   

Visco-Plastic Behaviour around Advancing Tunnels in Squeezing Rock   总被引：3，自引：1，他引：2  

D. Sterpi  G. Gioda 《Rock Mechanics and Rock Engineering》2009,42(2):319-339

Summary  The visco-plastic behaviour of rocks plays a relevant role in the tunnelling works, especially for deep tunnels subjected to large initial stresses for which squeezing conditions may develop. A rheological model is discussed that accounts for visco-elastic (primary) and visco-plastic (secondary) contributions to rock creep. The effects of tertiary creep are included in the model by way of a gradual mechanical damage governed by the cumulated visco-plastic strains. The parameters of the intact rock are first identified based on laboratory test results presented in the literature. Then, after scaling them to those of the rock mass, the potential applicability of the model is tested through axisymmetric and plane strain finite element analyses of the full face excavation of a deep circular tunnel. The results are discussed with particular reference to the short term redistribution of stresses around the opening and to its convergence. The analyses show the relevant influence of tertiary creep on the tunnel closure. In addition, those based on an axisymmetric scheme turn out to be crucial for the correct long term prediction of the interaction between the rock mass and the supporting structure of the opening.  相似文献   

两河口水电站母线洞开挖过程围岩破坏机制     

蒋雄  徐奴文  周钟  侯东奇  李昂  张敏 《岩土力学》2019,40(1):305-314

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地层渐进成拱对浅埋隧道上覆土压力影响研究     

汪大海  贺少辉  刘夏冰  张嘉文  姚文博 《岩土力学》2019,40(6):2311-2322

砂土及完整性较差、黏聚强度较小的破碎岩体中,浅埋隧道地层拱作用机制随地层变形发展而变化,受此影响隧道松动土压力也相应变化。常规方法忽略了地层拱不同阶段力学机制的不同,同时未考虑剪切面转动与大主应力旋转之间的相互关系,因此,不能解决浅埋隧道地层能否成拱、地层拱何时贯通至地表以及地层拱发展对隧道松动土压力影响等问题。针对这一情况,提出渐进地层拱力学模型以反映不同阶段地层拱的力学机制;其次,同时考虑主应力旋转、剪切面转动及二者相互关系,确定拱内土体应力分布;随后,优化了传统主应力偏转与地层差异沉降间的数学模型。在此基础上确定了渐进地层拱对隧道松动土压力的影响。改进方法结果与传统方法结果及试验结果的对比验证了改进方法的有效性与适用性。通过参数分析研究了隧道初始松动压力、随地层变形发展的松动压力以及地层拱贯通至地表时的极限变形等关键参数。最后,对下北山超大跨浅埋隧道的研究说明了改进方法的实用性。结论显示：（1）初始松动压力为初始松动区内土体重力,初始松动区范围不受覆跨比影响,而受地层强度影响,随内摩擦角增加而减小;（2）最大拱效应阶段以后,松动土压力随地层变形发展而增加,深埋、小跨度隧道（ ）增长速率较慢,反之较快;（3）极限变形随覆跨比、内摩擦角增加而增加,深埋、小跨度隧道地层拱效应更明显;（4）对于下北山隧道,初始地层拱存在,初始松动土压力为0.37 ,极限松动土压力为0.41 ,最终松动土压力为0.54 ,隧道变形应控制在5.7%以下避免地层拱贯通至地表。  相似文献