强降雨条件下堆积层边坡—邻近隧道相互作用机理及其鲁棒性设计方法研究

The deformation extrusion force of the deposit slope, caused by the strong rainfall, makes the surrounding rock pressure calculated with present method become bigger. While the uncertainty of the rock and soil parameters and their coefficients of variation can make the surrounding rock pressure bigger than the design value calculated with present method. Then the tunnel second supporting structure will deform and crack because the surrounding rock pressure is to big. That is to say the design scheme is not robust. Therefore, the calculation method of surrounding rock pressure and the tunnel optimal design method still need to do some research, meanwhile considering the interaction between the deposit slope and nearby tunnel. The model tests about the deposit slope and the excavation and support of nearby tunnel can be firstly carried out with typical working conditions. Meanwhile, the numerical models of different working conditions can be analyzed with the determined numerical modelling method and analysis method. Then the evolution law of the extrusion force caused by the deformation of the slope in space and time can be discussed based on the test monitoring and numerical analysis results. And the mechanical response of the tunnel supporting structure, caused by the extrusion force of the deposit slope, can be obtained. Secondly, the calculation model of the surrounding rock pressure can be proposed considering the action of the slope extrusion deformation. The stability analysis method of the tunnel supporting structure can also be presented. Then the stability analysis method of the deposit slope will be presented based on the proposed safety control standard of the surrounding rock pressure. Finally, the multi-objective programming model of robust design and its optimal analysis method can be obtained. Then the robust design method of tunnel supporting structure and deposit slope, which can still make them stable when the load and calculation parameters are uncertain and difficult to get the proper calculation values, can be present. The research results will make the design theory considering the interaction between slope and tunnel more reliable, which is important to the academic and engineering practice.

强降雨引起的堆积层坡体变形挤压力使围岩压力增大，而岩土参数及其变异系数的取值不确定性也可使围岩压力大于其设计值，两者均能导致隧道二衬因过载而变形开裂，即设计方案不具鲁棒性。因此，考虑坡体挤压变形作用的围岩压力计算方法及穿越堆积层边坡的隧道优化设计方法尚需深入研究。首先开展典型工况下穿越堆积层边坡的隧道开挖支护室内模型试验，并进行多工况数值试验，基于试验结果探讨坡体变形挤压力的时空演化规律，揭示隧道支护结构对坡体变形挤压力的力学响应机理；然后，提出考虑坡体挤压变形作用的围岩压力计算模型，构建隧道支护结构稳定性分析方法，进而确定围岩压力安全控制标准，并以此为目标建立出堆积层边坡稳定性分析方法；最后，确定多目标规划模型及其优化分析方法，建立出能承受荷载与计算参数取值不确定性的隧道与堆积层边坡鲁棒性设计方法。研究成果将完善和发展考虑相互作用的边坡与隧道支护设计理论，具有重要的理论与工程实际意义。

随着公路和铁路路网的延伸与发展，有许多山体隧道必须穿越堆积土层边坡，但相关设计理论研究仍存在不足。本项目以前期研究为基础，针对平行、垂直穿越堆积层两种隧道布置形式，通过模型试验、理论分析、数值分析对堆积层边坡与邻近隧道支护结构的相互作用机理进行研究，进一步提出提出合理的稳定性分析与支护设计方法及其安全控制标准，特别是强降雨条件下以隧道支护结构稳定安全为目标的堆积层边坡稳定性分析方法。开发了一种适用于隧道-边坡所持模型的装置；提出了二衬结构在堆积层坡体变形挤压力作用下承载、变形、开裂破坏的发展过程和规律；分析了不同施工阶段堆积层边坡与邻近隧道的位移和内力时空分布特征；提出不同参数取值对隧道二衬开裂的影响规律；提出了降雨入渗条件下，隧道穿越堆积体边坡的受力与变形机理，提出了一种基于结构荷载法下的滑坡诱发隧道开裂的裂缝宽度解析解算法，并和数值模拟进行了比对印证。研究成果对于阐明施工和降雨情况下穿越堆积层隧道的位移和变形机理具有重要意义，为今后穿越堆积土体的隧道设计提供了理论依据。