巴基斯坦N-J水电站地下厂房边墙变形分析

巴基斯坦N-J水电站地下厂房围岩岩性为软硬相间的砂岩与泥(页)岩,围岩类别以Q4为主,且节理裂隙发育;尾水闸门操作室设在主厂房内,局部形成大跨度的洞室,施工开挖过程中下游边墙产生较大的变形。经分析,厂房布置不合理是变形大的主要原因,而地质条件差则是控制因素,加剧了变形的发展。通过调整开挖次序和增强支护措施,围岩已趋于稳定。

Deformation and analysis of side wall of underground powerhouse of N-J Hydropower Station in Pakistan

The rock lithology for the underground powerhouse of N-J hydroelectric project in Pakistan is alternated beds of sandstone and mudstone (shale). The surrounding rock is mainly classified as Q4 with developed joint fissures. Tailrace gate chambers are located inside the main powerhouse cavern that locally forms a large-span underground cavern. Large deformation occurred on downstream wall during the excavation of the main cavern. Through analysis, it is concluded that the main cause of large deformation is unreasonable powerhouse arrangement, and the poor geological conditions are control factors intensifying the development of deformation. By adjusting the excavation sequence and enhancing the rock supporting measures, the surrounding rock mass has tended to be stable.