中文摘要：

雅砻江锦屏一级水电站地下厂房的监测结果显示,下游拱腰处混凝土喷层开始出现鼓出开裂现象,随后裂缝持续扩展,喷层大量剥落;同时,下游拱腰处围岩位移和锚杆应力也显著增加。经过详细的现场地质调查,并结合厂房的受力情况进行数值计算,分析厂房下游拱腰处围岩变形破坏及混凝土喷层开裂剥落的原因。研究结果表明：高地应力和偏压作用在下游拱腰部位形成高强度的应力集中是导致该部位混凝土喷层开裂剥落的主要原因,主变室的开挖和围岩中第四组结构面的普遍发育加剧混凝土喷层的开裂和剥落。

英文摘要：

Monitoring results show that a lot of concrete shotcrete layer has fell and cracked around the underground powerhouse of Jinping I hydroelectric power station,and then many shotcrete layer are spalling with the crack development. Meanwhile,displacement of surrounding rock and bolt stress in the downstream hance of the powerhouse increases particularly. The cause analysis of deformation and failure of surrounding rock and the crack and spallig of concrete shotcrete layer around the downstream hance of the powerhouse is conducted by detailed field geologic survey and numerical calculation according to the force condition of underground powerhouse. The research results indicate that high level of stress concentration formed by high geostress and eccentric compression are the major factors which lead the concrete shotcrete layer at corresponding position to crack and spall;and the excavation of main transformer chamber and universal development of the fourth discontinuities aggravate the process.