地震荷载作用下锦屏地下厂房动力分析

Dynamic Analysis of Jinping Underground Hydropower Station under Seismic Action

锦屏地下厂房洞室群规模巨大,厂区断层及裂隙密集带发育,实测最大主应力达35.7 MPa,为高地应力区。该区基本烈度VII度,50年超越概率5%的水平峰值加速度达到0.167 g,抗震问题突出。采用输入加速度时程法,对该地下厂房5#机组段二维有限元模型进行动力时程分析。结果表明:5#机组段进行系统支护后,在地震荷载作用下,三大洞室协调振动,上下游边墙处动位移及速度差异较小;厂区水平向及铅直向加速度约为2.7 m/s2和1.9 m/s2,分别为输入加速度的1.65和1.73倍;围岩动力破坏区及动拉应力区分布规律与静力作用下相近,但其深度和量值有所增加,且在局部区域有新拉应力区生成;动拉应力区深度在3.7 m以内,其量值一般小于0.2 MPa,说明加固措施有效,可以满足抗震要求。

The underground powerhouse of Jinping hydro-power station is composed of large cavern system. The surrounding rock consists of fault and fissure zone, with measured maximum geo-stress up to 35.7MPa, so the power house locates in high stress area. The basic seismic intensity of the dam site area is VII, the crest value of earthquake acceleration that 50 years beyond the probability of 5 % is 0. 167 g. In this paper, dynamic analysis was carried out on 2D finite element model of 5# unit sec- tion by inputting acceleration time-history wave. The result shows that under seismic action, three large caverns of 5# unit section were coordination vibrated after system support, and the acceleration of horizontal directional acceleration was 2.7 m/s2, while 1.9 m/s2in the Vertical direction, or in an- other word 1.65 and 1.73 times the input acceleration. The distribution regularity of dynamic failure zone and dynami depth and value c tensile stress zone of surrounding rock were close to which under static load, but the were increased, and the reinforcement measures can meet the seismic requirements.