Abstract: After the excavation of underground cavern, relaxation occurs in the surrounding rock of the cavern. Thus, determination of relaxation zone depth is important for evaluation of the stability of surrounding rock and for the design of tunnel support. In this paper, based on results of acoustic test during construction of underground powerhouse of Baihetan hydropower station, the relationship among rock relaxation, excavation depth and time is analyzed to provide basis for excavation and design of support.

Key words: rock relaxation, underground powerhouse, acoustic test

摘要： 地下洞室开挖后，在洞室围岩周围形成一定深度的松弛带，松弛带深度的确定对评价围岩稳定性和指导洞室支护设计都具有重要意义。基于白鹤滩水电站地下厂房开挖期间声波测试结果，分析地下厂房松弛与开挖深度、时间的关系，为指导施工开挖和岩体松弛加固设计提供依据。

关键词: 岩体松弛, 地下厂房, 声波测试