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Abstract It presents the in-situ tests on excavation damaged zone(EDZ) evolution of high sidewall surrounding rock mass in Houziyan hydropower station using microseismic monitoring and conventional testing methods such as multiple position extensometers，acoustic wave test and borehole TV. Firstly，through analyzing a series of conventional testing and microseismic monitoring results，deformation and failure characteristics of surrounding rock mass are revealed，and the evolution processes of surrounding rock fractures such as initiation，coalescence and extension are obtained during excavation unloading processes of underground powerhouse. Afterwards，the relationship among EDZ of surrounding rock mass，cracks evolution and construction status are also analyzed，which makes it possible for the whole procedure of cracks formation，development and close to be obtained. Finally，the depth of EDZ is recognized；the relationship between fractures evolution and construction progress is given；And the formation and evolution mechanism of EDZ is discussed as well. It will not only provide the direct data for geological exploration but also contribute greatly to excavation and support design and analysis of deformation behaviors of underground powerhouse. Some references can be thus provided for design and construction of similar underground engineering.
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2015, Vol. 34 
