猴子岩水电站地下厂房施工期围岩变形特征分析

Deformation Characteristics of Surrounding Rock during Underground Powerhouse Construction at Houziyan Hydropower Station

猴子岩水电站地下厂房岩体具有地应力高、强度应力比低的特点,在施工过程中出现岩体片帮、锚头内陷、喷混凝土层开裂等变形现象。研究成果表明:未开挖时间段内围岩声波波速和卸荷松弛深度以没有明显变化为主;开挖时间段内围岩岩体卸荷松弛深度多随逐层开挖由表及里增加、围岩声波波速多随逐层开挖由表及里衰减,表明猴子岩水电站地下厂房岩体变形以开挖后应力释放致岩体损伤以为主。

The rock mass in underground powerhouse of Houziyan hydropower station is characterized with high ground stress and low strength stress ratio. Deformation phenomenon such as rock mass spalling,anchor head invagination,shotcrete layer cracking occurred during construction. Research results show that acoustic wave velocity and relaxation depth did not change significantly in surrounding rocks during the non-excavation period; relaxation depth in rock mass increased from the outside to the inside layer by layer during excavation and the acoustic wave velocity of surrounding rock attenuated from the outside to the inside layer by layer during the excavation. Therefore,rock mass damage caused by stress release after excavation is considered as main phenomenon of rock mass deformation of underground powerhouse at Houziyan hydropower station