共查询到20条相似文献，搜索用时 359 毫秒
1.
This paper presents an analytical solution for the prediction of internal forces and displacements of a jointed segmental precast circular tunnel lining. The effects of joint stiffness on the performance of the tunnel lining are discussed. The ‘force method’ is used to determine the internal forces and displacements of jointed tunnel lining. Five shield‐driven tunnel cases are adopted to study the effects of joint stiffness, soil resistance, joint distribution and joint number on the internal forces and displacements of circular tunnels. Laboratory model tests are conducted to verify the proposed analytical solution. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
2.
3.
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
4.
隧道支护结构荷载作用的随机反演 总被引：7，自引：0，他引：7
提出荷载－结构模式进行随机反分析方法，从隧道支护结构变形反算对应的荷载作用，可反推围岩抗力系数和覆土荷载的分布情况，以及作用于支护结构上各部位的外荷载。提出了以实测位移为基础的样条函数插值．以插值位移补充大量的实测值，满足了反分析所需众多的已知位移数。通过一施工实例对该方法的可行性进行了检验。 相似文献
5.
分布荷载推力桩计算的p-y曲线法研究 总被引：2，自引：2，他引：0
为提高现有水平梯形分布荷载推力桩设计计算水平,提出了地基系数按非线性土抗力.水平位移(p-y)曲线抗力模式表达的水平梯形分布荷载推力桩位移和内力计算的有限差分数值分析方法,并详细推导了桩身位移的差分格式.基于这些公式,编制了全桩位移、内力及侧土抗力的计算和图形处理程序,可适用于滑坡抗滑桩和深基坑悬臂支护桩的设计计算.结合新型桩型现浇混凝土薄壁管桩(PCC桩)作为滑坡抗滑桩进行对比分析,算例表明:该方法方便可靠.当有限差分段划分得足够小时,可使数值解接近于真实解. 相似文献
6.
Three-dimensional numerical simulation for mechanized tunnelling in soft ground: the influence of the joint pattern 总被引：1，自引：1，他引：0
The main purpose of this study was to provide a three-dimensional numerical model, which would allow the tunnel lining behaviour and the displacement field surrounding the tunnel to be evaluated. Most of the processes that occur during mechanized excavation have been simulated in this model. The influence of the lining joint pattern, including segmental lining joints and their connections, has in particular been taken into consideration. The impact of the processes during mechanized excavation, such as the grouting pressure and the jacking forces in the structural forces induced in the tunnel lining, has been presented. These values depend on the tunnel advancement. However, a negligible influence of the joint pattern on the ground displacement field surrounding the tunnel has been observed. Generally, a variation in the structural forces in successive rings along the tunnel axis has been found in a staggered segmental lining, indicating the necessity of simulating the joints in the tunnel lining and using a full three-dimensional numerical model to obtain an accurate estimation. In addition, the considerable influence of the coupling effect between successive rings on the lining behaviour has been highlighted. 相似文献
7.
顶管矩形工作井复合式后背墙反力分布研究 总被引：1，自引：0，他引：1
顶管工作井在顶进施工过程中受力复杂,主要表现在：确定千斤顶推力在内部结构、围护结构和后背墙外侧土体之间的作用力是如何传递,土体变形对墙背土体抗力发挥的影响以及其对结构内力计算分析的影响。对现有顶管工作井计算方法进行归纳基础上,通过对工程算例建立数值计算模型,求证了后背墙各部分反力在宽度和深度方向上的分布规律,为探求一种合理简化更加接近实际的顶管复合式后背墙结构计算方法提供参照。 相似文献
8.
节理岩体中隧道开挖与支护的数值模拟 总被引：11，自引：0，他引：11
由于节理、断层等不连续面的存在造成岩体变形的不连续性,并且这些不连续面对岩体变形、应力等力学行为造成重要影响。对已有的非连续变形分析程序进行了两点改进,应用改进的程序模拟了节理岩体中隧洞开挖与支护的过程,研究了不同节理倾角岩体的应力分布特性、开挖后隧洞围岩的变形和应力分布规律以及支护后衬砌的变形与应力特点。研究结果表明,节理倾角对节理岩体系统的应力和变形有着直接的影响,并且影响着隧洞开挖后的内空收敛效应;隧洞开挖顺序对围岩的变形和稳定也有重要影响。改进后的非连续变形分析方法和程序可以用来分析复杂节理岩体系统中隧洞的开挖与支护。 相似文献
9.
Van-Manh Nguyen Heinz Konietzky Thomas Frühwirt 《Geotechnical and Geological Engineering》2014,32(4):829-846
A new procedure is presented, which combines big shear box tests on rocks and corresponding numerical simulations with explicit consideration of joint roughness to get deeper insight into the shear behavior of rock joints. The procedure consists of three parts: (1) constant normal load- or CNS-shear box tests with registration of shear- and normal-components of stress and displacements and deduction of basis rock mechanical parameters; (2) high resolution 3D-scanning of joint surface to deduce joint topography; and (3) set-up, run and evaluation of 3-dimensional numerical model with explicit duplication of joint roughness as back-analysis of shear box tests. The numerical back-analysis provides deeper insight into the joint behavior at the micro-scale. Several parameters can be deduced, like micro-slope angle distribution, aperture size distribution, local normal stress distribution and detailed analysis of dilation in relation to shear direction. The potential of the new procedure is illustrated exemplary by shear box tests on slate. 相似文献
10.
隧道斜交穿越地裂缝的模型试验研究 总被引：1，自引：0，他引：1
西安地区由北向南间隔分布有十多条近东西走向的地裂缝,建设中的多条地铁线路与地裂缝呈斜交状态。为了揭示地铁隧道斜交穿越地裂缝时受地裂缝活动而产生的力学性状变化,采用50:1几何相似比尺的物理模型试验仪,在合理模拟围岩地层、衬砌结构、应力条件、地裂缝与洞轴线交角及其错动位移基础上,开展了斜交地裂缝活动条件下隧道衬砌结构与围岩相互作用的物理模型试验研究,并与正交地裂缝活动下的测试结果进行了对比分析。表明斜交地裂缝活动对地铁隧道的影响范围更大,各变形缝均有明显的沉降差发展;邻近斜交地裂缝的衬砌结构易处于“悬臂梁”受力状态,衬砌结构不均匀沉降使其产生旋转位移,围岩土压力变化使衬砌结构内力产生显著变化;随着地裂缝错动位移的发展,上盘内拱顶和下盘拱顶、拱底出现围岩作用的加强,而上盘拱底出现围岩作用的松弛。与隧道正交穿越地裂缝的情况比较,斜交穿越地裂缝时围岩土压力和衬砌结构内力变化更大,易出现拉裂破坏。 相似文献
11.
通过对比修正惯用法的解析解、ANSYS数值模拟解和ANSYS梁-弹簧模型法数值模拟解,结合东莞至惠州城际轨道交通工程DK97+898.238~DK100+897段管片内力现场实测结果,深入探讨各计算方法的合理性和准确性,并得出以下结论:修正惯用法解析解管片内力及配筋最大,修正惯用法数值解次之,梁-弹簧法数值解与现场实测反算值最小。修正惯用法解析解偏保守,容易造成设计配筋过大和浪费;建模较为复杂的梁-弹簧法及现场实测可反馈设计,其结果表明,修正惯用法数值模拟结果比解析解更接近工程实际,本工程内比解析法可节省配筋22.6%左右,且仍有富余量。 相似文献
12.
13.
Analysis of shield tunnel 总被引：1，自引：0，他引：1
This paper proposes a two‐dimensional finite element model for the analysis of shield tunnels by taking into account the construction process which is divided into four stages. The soil is assumed to behave as an elasto‐plastic medium whereas the shield is simulated by beam–joint discontinuous model in which curved beam elements and joint elements are used to model the segments and joints, respectively. As grout is usually injected to fill the gap between the lining and the soil, the property parameters of the grout are chosen in such a way that they can reflect the state of the grout at each stage. Furthermore, the contact condition between the soil and lining will change with the construction stage, and therefore, different stress‐releasing coefficients are used to account for the changes. To assess the accuracy that can be attained by the method in solving practical problems, the shield tunnelling in the No. 7 Subway Line Project in Osaka, Japan, is used as a case history for our study. The numerical results are compared with those measured in the field. The results presented in the paper show that the proposed numerical procedure can be used to effectively estimate the deformation, stresses and moments experienced by the surrounding soils and the concrete lining segments. The analysis and method presented in this paper can be considered to be useful for other subway construction projects involving shield tunnelling in soft soils. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
14.
We present an explicit analytical approach for calculating the distribution of stress around a circular cased borehole in a general anisotropic formation. This approach is developed based on a pure elastic cased borehole model, which can include multiple cemented concentric casing strings that are surrounded by a homogeneous anisotropic medium. The wall of the innermost casing is under the compression of borehole internal fluid pressure, and the formation can be subjected to arbitrary far‐field stresses. Every casing–cement boundary is assumed to be welded, so as the cement–formation boundary. The derived analytical solution can be applied to an arbitrary wellbore trajectory in an arbitrary anisotropic formation and is also applicable to degenerate isotropic formations. Accuracy and robustness of the analytical solution is validated through comparing its results with those calculated from the classical Kirsch solution for an isotropic example that has identical elastic properties for all materials and from a finite element method for an anisotropic cased borehole example. 相似文献
15.
P. Yiouta-Mitra P. P. Nomikos E. Mertiri A. I. Sofianos 《Geotechnical and Geological Engineering》2013,31(2):647-665
Sensitivity analysis should be employed to examine the effect of the variability of selected parameters on critical response of a construction, using credible upper and lower bounds. This investigation performs such an analysis for an actual tunnel design case by means of numerical modeling. A local method, which is a partial derivative of the output with respect to several input factors, is used so as to ensure ease of use for the designer. In this way, the effect of varying geotechnical parameters over their possible values with respect to internal forces and displacements of the tunnel temporary lining is evaluated. The analysis includes not only assessment of the greatest influence on the item under observation by use of new types of diagrams that provide better comprehension but also a first order reliability evaluation on the effect of input parameters with respect to the reinforcement requirements of the temporary lining. 相似文献
16.
Analytical model for the mechanical behaviour of bolted rock joints subjected to shearing 总被引：5，自引：0，他引：5
Summary This study proposes a new analytical model for the prediction of the contribution of bolts to the shear strength of a rock joint. The main characteristics of this model are the accounts for the interaction of the axial and the shear forces mobilised in the bolt, as well as the large plastic displacements of the bolt occurring during the loading process. The complete curve of the bolt contribution as a function of the displacement along the joint can be computed, and the maximum bolt contribution is obtained by dissociating the bolt cohesion and the confinement effects. The comparison of the performances of this analytical model with test results shows its capacity to describe the observed phenomena. The effects of the most important parameters such as bolt inclination, mechanical properties of bolt material, rock strength and joint friction angle are clearly established and discussed. 相似文献
17.
节理岩体几何结构非常复杂,研究其渗流特性对于指导含水岩层稳定性分析具有重要价值。应用离散裂隙网络模型DFN方法,基于VC++6.0软件平台,建立了平面渗流分析方法,分析了节理岩体不同几何分布情况下的渗透率张量特征,通过定义渗流定向性系数对岩体渗流的定向性特征进行了定量分析。结果表明：单组节理岩体渗流具有明显的各向异性特征,渗流定向性随着节理角度变化显著;节理随着节理贯通性增加,节理渗透率呈现对数增加趋势;两组节理情况下,各向异性特征随着节理组间夹角变化;两组节理岩体渗流特征研究中,正交分布下,岩体仍存在各向异性,但渗流定向性系数较低;当节理倾角服从正态分布时,随着节理倾角标准差增大,渗透率增加;两组节理夹角不同时,节理渗透主方向倾角随着夹角增大而相应增大,基本沿两组节理夹角方向的角平分线方向。 相似文献
18.
复合式衬砌结构中衬砌分担围岩压力的评价方法是隧道工程技术的重要研究课题之一。依托某新建铁路隧道工程,提出了一种基于监测位移反分析评价围岩和支护应力,进而计算初期支护和衬砌背后压力的方法。根据监测位移和衬砌施作时间,确定初期支护的已发生变形和剩余变形。通过有限元反分析求出与已发生变形和剩余变形相对应的围岩和支护应力,得到初期支护和衬砌背后压力。对比初期支护背后压力及衬砌背后压力的现场监测和反分析的计算结果,两者比较一致,说明了该方法的可行性。该新建隧道初期支护闭合95 d后施作衬砌,计算得到衬砌背后压力约0.04～0.06 MPa,衬砌分担围岩压力比例约13%～16%。研究成果对复合式衬砌结构的设计具有一定的参考意义。 相似文献
19.
简谐荷载作用下饱和土体中圆形衬砌隧道三维动力响应分析 总被引：2，自引：0，他引：2
研究了全空间饱和土体中圆形衬砌隧道在径向简谐点荷载作用下的三维动力响应,将衬砌用无限长圆柱壳来模拟,土体用Biot饱和多孔介质模型来模拟,引入两类势函数来表示土骨架的位移和孔隙水压力,并利用修正Bessel方程来求解各势函数,结合边界条件,得到频率-波数域内衬砌和土骨架位移、孔隙水压力的解答,最后进行Fourier逆变换得到时间-空间域内的响应。通过算例分析了荷载振动频率和土体渗透性对土体和衬砌位移响应及土体孔压的影响。结果表明,饱和土体和弹性土体的位移响应具有明显区别。随着荷载频率的增大,土体和隧道位移幅值减小,土体孔压幅值增大;随着土体渗透性增大,土体位移及孔压幅值减小。 相似文献