轴对称隧道塑性应力分布及其松弛效应的半解析计算研究

发布时间：2018-10-19 06:43

【摘要】：隧道围岩的应力分布是隧道稳定性分析的基础,对应力分布做出正确的计算关系到整个隧道的施工期及持久性的安全。以往应力分布计算中的屈服准则存在一定局限性,因此,利用准确完善的隧道三维屈服准则计算围岩的应力分布情况,具有重要工程意义;时间本身就是影响隧道应力分布的重要因素,而应力松弛效应是应力在时间轴上的具体表现,应力松弛是岩体流变研究的一个重要的组成部分,但由于要完成应力松弛实验需要极为严格的条件,因此实现难度非常大,研究也相对较少。同时应力松弛的理论研究尚不充分,还需更多的理论性工作来揭示其实质。本文针对隧道开挖初期围岩的应力重分布及长期流变作用下的应力松弛效应,提出了基于GZZ准则三维非线性隧洞应力分布计算,并在此基础上加入时间因素,建立计算模型,对隧道围岩的应力松弛行为进行了研究,通过收集前人资料、理论分析推导及数值计算,实现了上述研究内容,并讨论其参数的确定方法,进行了塑性区围岩的应变计算及扩容和渗流力影响下的应力分布计算,计算了长期流变情况下的黏弹塑性围岩应力松弛的具体特征。此研究可以为隧道的稳定性设计提供参考,为工程施工提供一定的科学指导。本文的主要工作包括:1.对岩土类非线性破坏准则以及其在工程中的应用进行了相关介绍。并介绍了适用于隧道围岩的应力松弛模型及方程。2.基于三维非线性的GZZ准则对轴对称隧道的塑性区应力分布进行理论推导,并利用MATLAB编写有限差分程序对高阶微分方程进行计算。3.对考虑扩容,内摩擦角,渗流力等因素的隧道围岩进行了基于GZZ准则的应力分布推导计算。4.利用弹塑性应力分布的计算结果作为流变的初始应力场,围绕西原模型建立起隧洞黏弹塑性围岩应力松弛的理论计算模型,并考虑空间开挖面效应的影响,得到了与实际隧洞受力更相符的应力松弛结果。科学地讨论了流变模型的各个参数对围岩应力松弛的影响,并将理论计算与数值计算结果相对照,二者差别很小,说明了理论计算的正确性,可为工程实践提供参考。
[Abstract]:The stress distribution of tunnel surrounding rock is the foundation of tunnel stability analysis. The correct calculation of the stress distribution is related to the safety of the whole tunnel during the construction period and the durability. The yield criterion used in stress distribution calculation in the past has some limitations. Therefore, it is of great engineering significance to calculate the stress distribution of surrounding rock by using the accurate and perfect three-dimensional yield criterion of tunnel. Time itself is an important factor affecting the stress distribution of tunnel, and stress relaxation effect is the concrete expression of stress on the time axis, and stress relaxation is an important part of the study of rock mass rheology. However, it is very difficult to complete the stress relaxation experiment and the research is relatively few. At the same time, the theoretical study of stress relaxation is not enough, and more theoretical work is needed to reveal its essence. Aiming at the stress redistribution of surrounding rock in the early stage of tunnel excavation and the stress relaxation effect under the effect of long-term rheology, a three-dimensional nonlinear tunnel stress distribution calculation based on GZZ criterion is proposed in this paper. Based on the calculation model, time factors are added to the calculation model. The stress relaxation behavior of surrounding rock of tunnel is studied. By collecting the previous data, theoretical analysis and numerical calculation, the above research contents are realized, and the method of determining the parameters is discussed. The strain calculation of the surrounding rock in plastic zone and the stress distribution under the influence of dilatancy and seepage force are carried out, and the specific characteristics of stress relaxation of viscoelastic-plastic surrounding rock under the condition of long-term rheology are calculated. This study can provide reference for the stability design of tunnel and scientific guidance for engineering construction. The main work of this paper includes: 1. The nonlinear failure criterion of rock and soil and its application in engineering are introduced. The stress relaxation model and equation for surrounding rock of tunnel are introduced. 2. Based on the three-dimensional nonlinear GZZ criterion, the plastic zone stress distribution of axisymmetric tunnel is derived theoretically, and the finite difference program written by MATLAB is used to calculate the higher order differential equation. The stress distribution of surrounding rock of tunnel based on GZZ criterion is deduced and calculated considering factors such as expansion, angle of internal friction and seepage force. 4. Using the result of elastic-plastic stress distribution as the initial stress field of rheology, the theoretical calculation model of stress relaxation of tunnel viscoelastic-plastic surrounding rock is established around the Xiyuan model, and the influence of spatial excavating surface effect is considered. The stress relaxation results are more consistent with the actual tunnel stress. The influence of various parameters of rheological model on stress relaxation of surrounding rock is discussed scientifically. The difference between theoretical calculation and numerical calculation is very small, which shows that the theoretical calculation is correct and can be used as a reference for engineering practice.
【学位授予单位】：华侨大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U451

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