缓倾层状砂泥岩地下洞室块体失稳模式及稳定性分析  

UNSTABLE MODES AND STABILITY CALCULATION OF SLOWLY DIPPING LAYERED SANDSTONE AND MUDSTONE IN UNDERGROUND CAVERN BLOCKS

作　　者：张琪雪 肖先煊[1] 许模[1] 郭健[1] 邵玮玺 李京天 ZHANG Qi-xue;XIAO Xian-xuan;XU Mo;GUO Jian;SHAO Wei-xi;LI Jing-tian(State Key Laboratory of Geological Hazards and Geological Environment Protection,Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]成都理工大学地质灾害防治与地质环境保护国家重点实验室,成都610059

出　　处：《地质灾害与环境保护》2024年第4期64-72,共9页Journal of Geological Hazards and Environment Preservation

基　　金：地质灾害防治与地质环境保护国家重点实验室自主研究课题(SKLGP20212010)。

摘　　要：缓倾层状砂泥岩地层地下洞室开挖过程中,块体失稳将威胁施工安全并造成巨大经济损失。研究缓倾层状岩体地下洞室围岩稳定性具有重要意义。论文以某水电工程的砂泥岩地层地下洞室围岩为研究对象,通过对现场勘探平硐进行精细化地质调查确定了工程区内控制块体稳定的关键节理裂隙发育特征。基于力学分析提出了几种块体典型失稳模式,采用块体理论计算了失稳块体的潜在规模。在此基础上,进一步利用三维数值模拟对工程关键部位稳定性进行计算分析。研究表明:(1)砂泥岩岩层倾角在11°~15°之间,地下工程岩体主要的优势结构面共3组:N60°W/SW∠88°、N38°W/SW∠87°和N71°W/NE∠86°;(2)缓倾层状砂泥岩地下洞室块体失稳模式包括边墙单面剪切滑移-掉块、边墙双面剪切滑移挤出、顶拱层状剥离、顶拱掉块等4种模式;(3)块体失稳最大方量为23.667 m^(3),最小稳定性系数为0.695;(4)岩体的变形主要集中在洞室顶拱,距离砂泥岩地层交界位置越近,开挖影响越大,位移越大。本研究可为缓倾层状砂泥岩地下洞室施工安全提供技术支撑。During the excavation of underground caverns in gently dipping stratified sandstone-mudstone strata, block instability will threaten construction safety and cause great economic losses. It is of great significance to study the stability of underground cavern enclosure in gently dipping stratified rock. The thesis takes the underground cavern surrounding rock of sandy mudstone stratum of a hydropower project as the research object, and determines the key joints and cracks development characteristics that control the block stability in the project area through the refined geological investigation of the flat hole explored on the site. Based on the mechanical analysis, several typical destabilization modes of blocks are proposed, and the potential size of the destabilized blocks is calculated by using the block theory. On this basis, the stability of the key parts of the project was further calculated and analyzed using three-dimensional numerical simulation. The conclusions drawn are as follows:(1) the dip of the sandstone mudstone rock layer is between 11° and 15°, and there are three groups of main dominant structural surfaces in the underground engineering rock body, which are N60°W/SW∠88°, N38°W/SW∠87° and N71°W/NE∠86°;(2) the modes of block destabilization in underground caverns with gently dipping laminated sandy mudstone include four modes: one-sided shear-slip-drop of sidewalls, two-sided shear-slip-extrusion of sidewalls, laminated stripping of the top arch, and drop of the top arch;(3) the maximum square volume of block destabilization is 23.667 m^(3), and the minimum stability coefficient is 0.695;(4) the deformation of the rock mass is mainly concentrated in the roof arch of the cavern, in which the closer to the junction position of the sandstone and mudstone strata, the greater the impact of excavation and the greater the displacement. This study can provide technical support for the construction safety of underground caverns in gently dipping laminated sandy mudstone.

关 键 词：缓倾层状岩体 砂泥岩地层 围岩稳定性分析 块体理论 失稳模式 

分 类 号：P642[天文地球—工程地质学] P694[天文地球—地质矿产勘探] TU457[天文地球—地质学]