水库触发地震研究中二维与三维有限元模拟结果比较  

Comparison of 2D and 3D Finite Element Simulations in the Research of Reservoir Induced Earthquakes

作　　者：郑亮[1,2] 张怀[1,2] 孙玉军[1,2] 程惠红[1,2] 张贝[1,2] 石耀霖[1,2] 

机构地区：[1]中国科学院计算地球动力学重点实验室,北京100049 [2]中国科学院大学地球科学学院,北京100049

出　　处：《地震》2013年第4期162-171,共10页Earthquake

基　　金：国土资源部地壳深部探测项目(SinoProbe-07);国家重点基础研究发展规划项目(2008CB425701);十一五"863"计划信息技术领域面向地球系统模式研究的高性能计算支撑软件系统重点项目(2010AA012402)

摘　　要：紫坪铺水库蓄水载荷引起的库仑应力变化以及是否可以触发汶川MS8.0地震是地学界关注的一个热点问题。已有较多研究均建立在二维有限元模拟基础上,然而二维与三维结果存在较大差异,本文定量给出了该差异的大小。首先比较了有限元方法与解析方法求解半无限空间点载荷下弹性问题结果,确认了三维有限元计算在百万网格下具有足够的计算精度;然后数值计算并比较了二维、三维模型中紫坪埔水库蓄水的弹性力学及渗流效应。结果表明,总体上弹性加载会造成逆断层更趋安全,而水压渗透使其趋于危险,两者叠加仍然没有导致增加汶川地震危险性;但现有的二维有限元模拟夸大了真实结果,在汶川震源位置三维计算的应力大小仅为二维计算的1/3到1/4,因此在严格的讨论中必须使用三维建模。It has been widely discussed in geoscience community whether Coulomb stress change caused by Zipingpu reservoir loading activities has triggered the 2008 Wenchuan Ms8.0 earthquake.Many conclusions have come from 2D finite element simulations,which are quite different with the 3D results.In this paper,we quantitatively discussed the difference of the 2D and the 3D results.First,a comparison of the 3D finite element solutions and the analytic solutions was given to ensure the enough precision of the 3D finite element simulation with 1 million grid points.Then,the 2D and the 3D numerical solutions of the elastic effect and the seepage effect caused by Zipingpu reservoir were compared.The simulation results show that elastic load caused the thrust fault to be more secure,while the water pressure caused it to be more dangerous.The superimposed effect,however,didn＇t result an increase in the risk of Wenchuan earthquake.The comparison of the 2D and the 3D results show the 2D result exaggerated the truth.At the hypocenter of the Wenchuan earthquake,the computed stress of the 3D result is only 1/3 to 1/4 of the 2D result,thus in a serious study,3D modeling is necessary.

关 键 词：水库触发地震 库仑应力 有限元数值模拟 汶川地震 

分 类 号：P315.7[天文地球—地震学]