高地应力断层破碎带衬砌力学特性对比与分析

以高地应力区某穿越断层破碎带隧道为工程依托,通过三维数值模拟来分析随着掌子面推进过程中的围岩空间应力场的状态及其变化趋势。首先,根据弹性衬砌模型计算结果判断衬砌结构是否还处于弹性状态;其次,按照弹塑性衬砌模型进行某穿越高地应力断层破碎带隧道三维数值模拟。计算结果表明:高地应力区穿越断层破碎带隧道三维数值模拟应该采用弹塑性衬砌结构;弹性计算模型与摩尔—伦计算模型分别计算所得衬砌结构关键点位移量差别较大,弹性衬砌模型计算得到关键点位移均小于摩尔—库伦衬砌模型所得到的量值,且约为摩尔—库伦模型计算所得量值的50%;拱顶和拱腰主应力波动范围在掌子面通过z=-50 m平面前0.5B(B为隧道宽度)和通过后1.5B范围,墙脚主应力波动范围在掌子面通过前1B和通过后0.5B范围;弹塑性衬砌计算的主应力较弹性衬砌计算的主应力大;揭示了某穿越高地应力断层破碎带隧道衬砌的破坏形式与潜在破坏面。

Comparison and Analysis of Mechanical Properties of Lining in Fault Fracture Zone with High Geostress

On the basis of a given tunnel through fault fracture zone with high ground stress,the paper analyzes the spatial distribution of stress field of rock mass by simulation with 3D numerals. First,the lining structure in elastic state is determined based on the calculation results of elastic lining model.Second,lining structure as elastic-plastic one is assumed to simulate the excavation with Finite Difference Software FLAC3 D. The results show that elastic-plastic lining structure should be used when a tunnel running through high ground stress and fault fracture zone is simulated; there is a big difference between elastic lining structure and elastic-plastic lining structure when they are applied to simulate the dynamic process of excavation respectively and displacement at the key-points in the elastic model; approximately50% of key-points displacement in Mohr-Coulomb model is smaller than that in Mohr-Coulomb model;the disturbance range of principal stress at crown and at side is 0. 5B( B is the width of tunnel) before z=-50 m( central plane) plane and 1. 5B after z =-50 m; the disturbance range of principal stress at side foot is 1B before z =-50 m and 0. 5B after z =-50 m; the principal stress of elastic-plastic lining structure is higher than that of elastic lining structure; and the research reveals failure mode and potential failure surface.