猴子岩水电站地下洞室群围岩松弛损伤控制技术

Control Technology of Loosing Surrounding Rock and Damage of Underground Cavern Group in Houziyan Hydropower Station

猴子岩水电站地下洞室群跨度大、地应力高、中主应力和最小主应力非常高,且与厂房轴向大角度相交,易导致大型地下厂房边墙发生劈裂破坏或损伤。根据地下洞室群施工期围岩损伤声波监测等资料分析,地下厂房损伤区主要分布在边墙浅层岩体4~5m范围内,高边墙局部部位损伤区分布在7~10 m范围,最大达11.8m。从开挖施工程序、围岩支护加固参数和时机两方面着手,采取了深层预裂、薄层开挖、随层支护的施工程序,由表及里、由浅入深、柔强结合的支护策略和快速支护加固机制,研究采取了下层超前和自进式锚杆预固灌,预应力锚杆一次注浆快速施工等工艺措施,从而控制了高地应力地下洞室开挖施工过程中的围岩损伤深度和发展程度。

The underground cavern group of the Houziyan Hydropower Station has a large span and high ground stress.The medium principal stress and the minimum principal stress are very high and they intersect with the axis of the underground powerhouse at a large angle,which is easy to cause splitting destruction or damage to the side wall of the large underground powerhouse.Based on the sound wave monitoring data of surrounding rock damage during the construction of the underground cavern group,the damage zone of the underground powerhouse is mainly distributed in the shallow rock mass of the sidewall within 4-5 m.The local damage area of the high side wall is distributed in the range of7-10 m,with the maximum of 11.8 m.Starting with the two aspects of excavation construction procedures and surrounding rock support,the construction procedures of deep pre-splitting,thin-layer excavation,and layer-to-layer support were adopted.Supporting strategy and rapid support and reinforcement mechanism that combine from the surface to the inside,from shallow to deep and from soft to strong were adopted.The research adopted technological measures such as advanced and self-advanced anchor pre-fixed grouting of the lower layer,and rapid grouting of pre-stressed anchors.Thus,the damage depth and development degree of surrounding rock were controlled during excavation of underground cavern with high ground stress.