安全监测是地下洞室围岩稳定安全评价的重要手段。乌东德水电站右岸地下厂房规模巨大,主厂房、主变洞、调压室三大洞室平行布置。为确保施工期围岩的安全稳定,通过使用多点位移计、锚杆应力计、锚索测力计、锚杆测力计、测缝计等监测仪器,对围岩表面和深部的变形进行监测,分析了地下厂房三大洞室第Ⅰ—第Ⅲ层开挖的位移特性与变形规律。监测结果表明:开挖引起的上层围岩变形较小,且主要集中在浅表层;三大洞室岩锚梁高程以上最大变形为16.43 mm,主厂房顶拱、上游侧岩锚梁和尾水调压室上游边墙围岩变形较大;爆破开挖扰动、开挖引起的空间效应以及较差的地质条件是围岩变形增长较快的主要影响因素;通过采用加强支护等措施,能有效控制围岩变形的发展。

Safety monitoring is an important means to assess the stability safety of surrounding rock. The right bank underground powerhouse of Wudongde hydropower station is huge with three large caverns (main powerhouse, main transformer cavern, and surge chamber) parallel to each other. In order to ensure the safety stability of surrounding rock during construction, we monitored the surface and deep deformations of surrounding rock by using multi-point displacement meter, anchor stress gauge, anchor dynamometer, and joint meter. We also analyzed the displacement characteristics and deformation regularity of the three large caverns. Monitoring results show that the deformation caused by excavation is small, mainly concentrating in the shallow surface; maximum deformation of surrounding rock above the height of rock anchor beam in the three caverns is 16.43 mm. Large deformation appears at the top of the main power house, upstream side rock anchor beam and upstream side wall of tail-water chamber room. Moreover, the rapid development of deformation is greatly influenced by blasting disturbance, space effect caused by excavation, and weak geologic condition. Timely and strong support measures could limit the development of deformation.