周宁水电站交通洞地应力测量结果及局部岩爆分析

Crust stress measurement results obtained at communication tunnel of Zhounin hydro-power-station underground workshop and local rock burst analysis

一、前言周宁水电站是正在建设中的一座大型高水头引水发电站。其可利用的水头落差达430多米,装机容量25万kW。厂房主交通洞高10m,宽12m。开挖到距洞口340m处时,在洞顶发生了岩爆,岩石发生崩落并伴有响声,给正在进行的施工工作带来一定的困难。同时工程技术人员十分关注围岩与洞室的稳定与安全,为分析岩爆的成因和洞室围岩中的应力状态,我们在岩爆部位以及地下厂房探洞内均进行了地应力测量。根据测量结果结合局部岩爆部位实地调查分析研究认为,发生岩爆的洞段是一个局部的高应力区,洞室开挖导致了围岩的应力集中,使得在应力调整—释放—平衡的过程中引发了岩爆。

Taking aim at local rock burst in the underground workshop cavity,we have investigated some problems concerning the basic generating conditions of local rock burst,exterior factors of wall rock stress concentration,empirical criterion of rock burst and the relation between wall rock stability and orientation of principal stress by using stress measurement data,that hydro-fracturing technique is adopted.It has been proposed that the cause of local rock burst in the communication cavity is the combined action of tectonic stress adding with topographic stress.