复杂地质条件下地下泵站洞室围岩稳定性分析

Stability analysis of surrounding rock in underground pumping station caverns under complex geological conditions

摘要

公明水库—清林径水库连通工程中的坂苗地下泵站洞室规模大，地质条件复杂，给工程开挖支护设计带来了诸多挑战。采用数值模拟方法对地下泵站洞室群的整体稳定性、开挖支护参数及关键块体等方面开展了分析研究，数值计算结果表明：地下泵站洞室群区域地应力较低，第一主应力方向与泵房长轴边墙交角约14°;施加系统支护措施后，洞周围岩变形和塑性区明显减小；减小锚杆支护密度(间排距1 m×1 m→1.5 m×1.5 m)除对断层F1分布区域有一定影响外，其余区域不明显；锚杆和锚索受力较大区域主要集中断层F1与蚀变带分布区域；仅根据钻孔揭示的结构面确定位置进行块体搜索，得到的块体均属于无限块体；搜索到7个体积较大的(> 180 m³)的随机块体，所有随机块体考虑锚固支护措施后的安全系数均大于2.0,满足块体安全系数的要求。

Abstract

The Banmiao underground pumping station in the Gongming Reservoir Qinglinjing Reservoir Connection Project has a large scale of underground caverns, and complex geological conditions, which pose many challenges to the excavation and support design of the project. Numerical simulation method were used to investigate the excavation construction, support parameters, key blocks, and other aspects of the underground pumping station caverns. The numerical result showed that the geostress in the underground pumping station caverns is relatively low, and the direction of σ₁ intersected with the long axis side wall of the pump room by about 14 °. After applying systematic support, the deformation and plastic zone of the surrounding rock around are significantly reduced. Reducing the density of bolt(spacing of 1 m × 1 m → 1.5 m × 1.5 m) has a certain impact in the area of fault F1, but it is not significant in other areas; The areas with high stress on bolts and cables are mainly located in the areas of fault F1 and alteration zones; Based on the joints' information in boreholes, it is found that all of the potential blocks belong to infinite blocks using the Block Stereographic Projection Method. Seven large(> 180 m³) random blocks were found during the search, and all random blocks had a safety factor greater than 2.0 after considering anchoring support measures, meeting the requirements for the block safety factor.

关键词

坂苗地下泵站 / 复杂地质条件 / 蚀变带 / 围岩稳定性分析 / 块体稳定

Key words

Banmiao underground pumping station / complex geological conditions / erosion zones / stability analysis of underground caverns / block stability

Author summay

孟 刚(1981—), 男, 高级工程师, 硕士, 主要从事水工结构工程设计。E-mail: [e-mail]