高地应力下围岩蠕变对隧道结构长期安全性的影响分析

发布时间：2018-01-04 02:24

本文关键词：高地应力下围岩蠕变对隧道结构长期安全性的影响分析　出处：《西南交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着我国经济社会的发展和西部大开发的快速推进,西部艰险山区的隧道工程也越来越多。这些隧道大多具有"长、大、深埋"的特点,且由于构造应力场的影响,围岩的蠕变效应会导致衬砌结构所受外荷载随着时间的增加不断增大,从而影响结构长期服役的安全性。本文依托篮家岩隧道工程,通过理论分析、室内试验和数值模拟等手段,开展了高地应力条件下围岩蠕变对隧道结构长期安全性的影响研究。主要研究工作如下:1.采用岩石力学系统与声发射测试系统开展了室内单轴和三轴压缩试验,并绘制岩石的应力-应变全过程曲线,对不同围压与不同含水状态下深埋碳质板岩的物理力学特性进行了研究。研究发现,水对碳质板岩的力学特性及其破裂特征具有明显的软化效应;碳质板岩的力学参数随着围压的增大而增大;低围压条件下岩石强度低,岩石的破裂更为迅速和突然,而高围压条件下岩石的渐进破裂特性更为显著,延塑性增强。2.采用快速拉格朗日有限差分软件建立了地层-结构三维数值模型,在该模型中,围岩采用基于M-C屈服准则的伯格斯蠕变模型(Cvisc模型)以考虑围岩的粘弹塑性效应对隧道结构长期安全性的影响。基于该模型,揭示了不同构造应力场对二次衬砌结构长期安全性能的影响。计算结果表明,构造应力场会对二次衬砌的长期安全特性产生显著影响,不同构造应力下二次衬砌达到临界安全状态的位置与大修时刻点存在显著区别。3.采用地层-结构三维数值模型,研究了围岩蠕变对裂损二次衬砌安全性能的影响。数值模型中,采用interface界面单元模拟裂损二次衬砌,二次衬砌的裂损程度采用裂缝截面的刚度折减系数η表示。考虑二次衬砌的不同裂损程度以及不同裂缝数量与开裂位置的组合,探明了不同工况下裂损二次衬砌结构内力和安全系数随时间的变化规律。计算结果表明,裂损程度对开裂位置处截面安全系数的影响较为明显,而对未开裂位置处截面安全系数的影响较小;二次衬砌的安全系数随着裂纹数量的增加而减小;不同裂损工况下二次衬砌达到临界安全状态的位置与大修加固时间存在显著差异。
[Abstract]:With the development of our country's economy and society and the rapid development of the western region, there are more and more tunnel projects in the western hard and dangerous mountain areas. Most of these tunnels have the characteristics of "long, large and deep buried". Because of the influence of tectonic stress field, the creep effect of surrounding rock will cause the external load of lining structure to increase with the increase of time, thus affecting the safety of the structure in service for a long time. Through theoretical analysis, laboratory tests and numerical simulation and other means. The influence of surrounding rock creep on the long-term safety of tunnel structure under high in-situ stress is studied. The main work is as follows:. 1. Uniaxial and triaxial compression tests were carried out with rock mechanics system and acoustic emission test system. The stress-strain curves are drawn and the physical and mechanical properties of deep buried carbonaceous slate under different confining pressures and different water-bearing states are studied. Water has obvious softening effect on mechanical properties and fracture characteristics of carbonaceous slate. The mechanical parameters of carbonaceous slate increase with the increase of confining pressure. Under the condition of low confining pressure, the strength of rock is low, the fracture of rock is more rapid and sudden, and the progressive fracture of rock under high confining pressure is more obvious. In this model, a three-dimensional numerical model of stratigraphic structure is established by using the fast Lagrangian finite difference software. The Boggs creep model based on M-C yield criterion and Cvisc model are used to consider the influence of visco-elastoplastic effect of surrounding rock on the long-term safety of tunnel structure. The effects of different tectonic stress fields on the long-term safety performance of secondary lining structures are revealed. The calculation results show that the structural stress field will have a significant impact on the long-term safety characteristics of secondary lining. There is a significant difference between the position of the secondary lining under different tectonic stresses and the critical safety state of the secondary lining and the moment point of overhaul. 3. A three-dimensional numerical model of stratigraphic structure is used. The influence of the creep of surrounding rock on the safety performance of the secondary lining with crack is studied. In the numerical model, the interface interface element is used to simulate the secondary lining. The cracking degree of the secondary lining is expressed by the stiffness reduction coefficient 畏 of the crack section, and the combination of the number of cracks and the crack location is considered. The variation law of internal force and safety factor of the secondary lining structure with time under different working conditions is investigated. The calculated results show that the degree of crack damage has an obvious effect on the safety factor of the section at the crack location. However, the effect on the safety factor of the section at the uncracked position is relatively small. The safety factor of the secondary lining decreases with the increase of the number of cracks. There are significant differences between the position of the secondary lining under different cracking conditions and the time of overhaul and reinforcement.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U451

【参考文献】