某水电站地下厂房开挖过程中稳定性初步分析

Preliminary analysis of underground powerhouse stability during excavation phase for a certain hydropower station

西南地区某水电站地下厂房规模较大,最大跨度31.10 m,最大高度78.0 m,地质条件特殊,且属于高地应力区。开挖过程中,厂房上游边墙出现阶段性变形速率较快,且时间-位移曲线收敛不明显的现象。为确保厂房开挖的安全,本文主要从地质角度,结合类似工程,分析了厂房上游边墙是否存在不稳定块体,变形速率较快以及变形量较大的原因,对厂房上游边墙围岩稳定性进行分析,并提出了初步解决方案。

The underground powerhouse of a certain hydropower station has larger scale with the largest span of 31.10 m and the maximum height of 78.0 m in southwest China.The geological conditions of underground powerhouse are special and belong to the high field stress areas.During the process of excavation,the upper boundary wall of the powerhouse appears some phenomenon that the rate of stage deformation is faster and the convergence of time-displacement curve is unobvious.Combined with similar projects,the paper analyzes the cause of the faster deformation rate and the large deformation and if there are unstable blocks in the upstream side wall from the angle of geology to ensure the excavation safety of underground powerhouse.The paper discusses the stability of surrounding rock for the upper boundary wall of the powerhouse and puts forward a preliminary solution.