彭水地下电站围岩稳定性分析

在分析彭水地下厂房地质条件的基础上，采用3DEC程序建立了3#机组部位三维离散元数值计算模型，对地下厂房开挖支护全过程进行了计算，详细分析了围岩变形情况、应力状态、塑性区分布及稳定性影响因素。计算结果反映：按基本计算条件，地下厂房开挖支护后，围岩整体稳定性良好。受开挖及结构面空间组合作用，上、下游边墙部位变形量在15? 35 mm左右；边墙变形主要发生在从其开挖往下的2?3级开挖步之内，从整个厂房开挖来分析，223.0?201.0 m高程开挖阶段对围岩稳定影响最重要；围岩稳定主要受层面、软弱夹层及贯通节理特性及其切割块体在开挖临空面的位置控制，局部分布的页岩本身变形及地应力因素对围岩稳定性影响相对较小。

Numerical analysis of stability of underground cavern surrounding rockmass of Pengshui Underground Power Plant

Based on an analysis of engineering geology conditions of Pengshui Underground Plant, the 3-dimensional distinct element numerical model is established. The excavation and reinforced process of underground powerhouse of Pengshui project are analyzed by using 3DEC. The pattern of deformation, stresses state, distribution of plastic regions caused by excavation and influence factors of cavern surrounding rock are studied. Several conclusions are drawn: the whole stability of excavated and reinforced surrounding rock is good according to this paper’s calculation conditions; the displacement of upstream and downstream walls are about 15~35 mm under excavation and control of discontinuous combination; the mostly deformation of cavern walls are completed from excavated to subsequent 2~3 excavation steps. the excavation phases from 223.0 m to 201.0 m are important to stability of cavern walls; the characteristics of lay, interlay and continuous joints and the blocks location cut by discontinuous have significant effect on surrounding rock stability, but local shale deformation and geostress have little influence on the stability of cavern walls.