DEFORMATION CHARACTERISTICS AND FEEDBACK ANALYSIS OF SURROUNDING ROCK OF LARGE UNDERGROUND POWERHOUSES EXCAVATED IN STEEPLY DIPPED SEDIMENTARY ROCK STRATA
Abstract：The deformation and failure characteristics of the surrounding rock of the high side wall of underground powerhouses of Pengshui Hydropower Station，corresponding supporting and processing scheme and the monitoring results，are described. Then dynamic feedback analysis is performed and the result is given. The result shows that the stability of high side wall is very critical when excavating large underground caverns in steeply dipped sedimentary rock strata；the deformation and stability of the surrounding rock is primarily dominated by weak structure plane and bedding plane. For the high side wall with steep dip angle and consequent rock strata，the deformation and failure mode of surrounding rock are typical sliding along the bedding plane；and for the high side wall with steep dip angle and obsequent rock strata，the deformation and collapse are caused by tension crack，break off and toppling. The results of feedback analysis based on the deformation monitoring data can provide important references to dynamic support design and information construction of the underground powerhouses.
