不同侧压系数下复合地层变形破坏特征数值模拟

针对中国中西部挤压造山带大埋深不同侧压系数(0.5~2.0)下复合地层在工程开挖扰动下复杂叠加的变形破坏特征，采用有限差分程序FLAC3D对3种不同组合型式的复合地层开展了数值模拟研究。同时结合软岩和硬岩解析解的分析对比，发现开挖卸荷作用下复合地层位移量比均质软岩小，前者随侧压系数增加位移量较大的点由顶拱向边墙转移变化。硬岩中富集的主应力比软岩中高。软岩塑性区半径最大的是前软后硬型，比上下叠置型复合地层的结果大很多。后者接近该深度下的均质软岩隧道的塑性圈半径。本文结果可为复合地层中隧道工程设计和施工提供参考。

Numerical simulation of deformation and failure characteristics of mixed ground under different lateral pressure coefficients

In view of the deformation and failure characteristics of mixed ground under different lateral pressure coefficients (0.5~2.0) excavated at large burial depth in the central western China compressional orogenic belt, the finite difference program FLAC3D was used to simulate the deformation and failure of three different construction types of mixed ground. At the same time, combined with the analysis and comparison of the analytical solutions of homogeneous soft rock and hard rock, it is found that the displacement of mixed ground during excavation is smaller than that of homogeneous soft rock, and the displacement of the former changes to the side wall with the increase of lateral pressure coefficient. The main stress in hard rock is higher than that in soft rock. The largest plastic radius of soft rock is the type of former soft and later hard type, which is much larger than that of the upper and lower superimposed types of mixed ground. The latter is close to the plastic circle radius of homogeneous soft rock at this depth. The result could be used for tunneling design and safety construction.