大柳树坝址工程断错效应分析

ENGINEERING EFFECTS TO DALIUSHU DAM SITE DUE ACTIVE DISLOCATION OF ADJACENT FAULTS DURING MAJOR EARTHQUAKES IN QINGHAI-TIBET PLATEAU

坐落于中卫-同心活动断裂带中间部位的黄河黑山峡大柳树坝址，距F201发震断层垂直距离不足1．5kin。统计表明，在青藏高原及其周缘地区，当发生Ⅶ级以上破坏性地震时，距发震断裂两侧3～5kin的范围内都有可能出现断层的分支破裂、次生破裂等错断效应。大柳树坝址处于Ⅶ级以上地震时的分支破裂发生带内，因此，存在工程错断效应问题。三维有限元数值模拟结果表明，断层F201发生错动时，坝址地段断层F93、F39、F40相对于F201的错动比率处分别达到14．38％、12．00％和9．84％以上。

The Daliushu Dam Site in the Heishanxia Gorge of the Yellow River is seated in the middle of Zhongwei - Tongxin active fault zone. It is apart 1.5 km from the seismogenic fault F201. The results of statistics indicated that the rupturing effects such as branch fractures and secondary fractures will be appeared around the adjacent 3 ～ 5 km area from seismogenic fault, if the Ms ≥7.0 Earthquakes happen in the Qinghai - Xizang plateau and its mar- gins. The Daliushu Dam Site is located in the zone of branch fracture occurrence when Ms ≥7, 0 Earthquakes happen. , So, engineering rupturing effects will be in existence. Result of 3 - D finite element analysis indicates that the dislocation ratio of the faults F93, F39, and F40 relative to the fault F201 arrives at 14.38% ,12.0% and 9.84% respectively, when the rupturing effects of fault F201 happen.