高地应力下双江口地下厂房围岩破坏特征及影响因素分析

双江口水电站作为大渡河流域水电梯级开发的上游控制性重点水库工程,受深山峡谷地域条件影响,地下厂房存在埋深大且地应力高的工程特点。以主厂房为研究对象,统计归纳了爆破开挖中现场围岩变形及破坏特征,并阐释了高地应力条件下岩体破坏机制及影响因素。研究结果表明,双江口水电站地下厂房爆破开挖过程中围岩主要发生板裂、板片状破裂、V型破裂以及应力与结构协同作用破坏四种主要类型。其中,板状破裂主要发育在边墙、顶拱及掌子面;板片状破裂和V型破裂主要发育在拱肩部位,破裂深度一般大于40 cm;应力与结构协同破坏围绕断层或节理聚集区,破坏规模不等且可预见性较差。

Analysis of Surrounding Rock Failure Characteristics and Influencing Factors of Shuangjiangkou Underground Powerhouse Under High Ground Stress

As a key upstream control reservoir project for the cascade development of hydropower in the Dadu River Basin, the Shuangjiangkou Hydropower Station is influenced by the conditions of mountain canyons, and the underground powerhouse has the engineering characteristics of large burial depth and high ground stress. Taking the main power house as the research object, the deformation and failure characteristics of on-site surrounding rock during blasting excavation were statistically summarized, and the rock blasting mechanism and influencing factors under high ground stress conditions were explained. The research results indicate that during the blasting excavation process of the underground powerhouse of Shuangjiangkou Hydropower Station, the surrounding rock mainly undergoes four main types:plate cracks, plate like fractures, V-shaped fractures, and stress structure synergistic failure. Among them, plate shaped fractures mainly develop on the side walls, top arches, and face of the tunnel; Plate shaped and V-shaped fractures mainly develop at the arch shoulder, with a fracture depth generally greater than 40 cm; Under the synergistic effect of stress and structure, the surrounding rock failure revolves around faults or joint aggregation areas, with varying scales of failure and poor predictability.