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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。
I. Introduction Zhouning Hydropower Station is under construction in a large high water head diversion power station. Its available head drop of more than 430 meters, installed capacity of 250000 kW. Factory owner traffic hole 10m high and 12m wide. Rock excavation occurred at the top of the tunnel at a distance of 340m from the entrance of the tunnel. The rock broke down and accompanied by sound, which brought some difficulties to the ongoing construction work. At the same time engineering and technical personnel are very concerned about the stability and safety of surrounding rock and caverns. In order to analyze the cause of rockburst and the stress state in the surrounding rock of the cavern, we conducted in-situ stress measurement in the rockburst site and the underground cavern. According to the results of the survey and the field investigation and analysis of the local rockburst sites, it is considered that the rock burst section is a locally high stress zone, and the excavation of the cavern leads to the stress concentration of the surrounding rock so that during stress adjustment-release-balance process Triggered a rock burst.