摘要:
坐落于中卫—同心逆冲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1.5km。在坝址区内,中卫—同心断裂带由数条断层组成,并可进一步分为主干断层、分支断层。这些断层与主干断层F201具有密切关系。统计表明,在青藏高原及其周缘地区,当发生7级以上破坏性地震时,距发震断裂两侧3~5km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。晚更新世以来沿F201发生过多次地震破裂事件,大柳树坝址处于7级以上地震时的分支破裂发生带内,因此存在工程错断可能。三维有限元数值模拟结果表明,F201发生错动时,坝址地段分支断层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。
Abstract:
The Daliushu dam site in the Heishanxia Gorge of the Yellow River is located in the middle of Zhongwei-Tongxin overthrust nappe fracture zone,which is 1.5km apart from the seismogenic fault F201.In the damsite area,the fracture zone is composed of many faults,and the faults can be divided into main faults and branch faults,which have a close relation with the fault F201.The results of statistic indicates that the rupturing effects as branch fracture,secondary fracture will be appeared around the 3-5km area apart from seismogenic fault when the Earthquakes with Ms ≥7.0 happen in the Qinghai-Tibet Plateau and its margins.Since late Pleistocene,the earthquake rupture events have happened along the fault F201 time after time,and the Daliushu dam site is located in the branch fracture zone when the earthquakes with Ms ≥7.0 happen,so it is possible for the engineering rupturing.Analysis result of 3D finite element indicates that the dislocation ratio of the fault F93,F39 and F40 to the fault F201 arrives at 14.38%,12.0% and 9.8% separately,when the rupturing effects of fault F201 happens.
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