考虑卸荷效应的深埋隧洞围岩分区破坏数值模拟

基于卸荷岩体力学基本理论，运用三维有限差分软件，提出以塑性体积应变增量变化区间与不同卸荷区域岩体力学参数相对应的卸荷模拟方法，模拟了不同侧压系数条件下开挖洞周附近围岩最大体积应变增量以及围岩损伤范围的变化情况。数值模拟结果表明：当侧压系数较低时，洞周附近围岩的塑性体积应变增量区域的外边界近似为竖向椭圆形，随着侧压系数的增大，其外边界逐渐向圆形变化，最后变为横向椭圆形。侧压系数越大，围岩的卸载效应越显著，洞周附近围岩的塑性体积应变增量就越大，其所产生的围岩损伤范围也相应越大。利用所获得的结果，可以为深埋隧洞的稳定性分析以及支护设计提供依据。

Numerical simulation of zonal cracking of deep tunnel surrounding rock considering unloading effect

Based on basic theory of unloading rock mass mechanics,a simulation method of unloading which the change intervals of plastic volumetric strain increment are corresponding to mechanical parameters of rock masses in different unloading zones is put forward by using three-dimensional finite difference software.Changes of the maximum volumetric strain increment and damage area of surrounding rock at different lateral pressure coefficients combination conditions are simulated.The results of numerical simulation show that,the external surface of area of plastic volumetric strain increment near the hole wall is approximately like an vertical oval at lower lateral pressure coefficient.With the lateral pressure coefficient increasing,the external surface of area of plastic volumetric strain increment becomes more rounded,and finally to a horizontal oval.The greater the lateral pressure coefficient,the unloading effect of surrounding rock is more significant and plastic volumetric strain increment of surrounding rock near the hole wall is greater,so the damage area of surrounding rock is correspondingly greater.The results provide foundation for the stability analysis of deep tunnel and supporting design of the cracked surrounding rock.