地球物理学报  2013, Vol. 56 Issue (6): 2133-2139 PDF

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

A discussion on "The mechanism of long-distance jumping and the migration of main active areas for strong earthquakes occurred in the Chinese continent"——transverse isotropic "wounded element" is a better method
DONG Pei-Yu1,2, SHI Yao-Lin1,2
1. Key Laboratory of Computational Geodynamics, Chinese Academy of Sciences, Beijing 100049, China;
2. College of Earth Science.University of Chinese Academy of Sciences, Beiing 100049, China
Abstract: In a paper titled "The mechanism of long-distance jumping and the migration of main active areas for strong earthquakes occurred in the Chinese continent "(Vol.55, No.1 of Chinese J.Geophys.(Chinese Edition)), Yang et a1.proposed to simulate the effects of earthquake fault slip by reducing shear modulus of the elements in calculation.Although this method can simulate the shear stress drop of a fault under compression and shear, it will produce a significant drop of normal stress on the fault which is incorrect.In this paper, we propose a better method——transverse isotropic "wounded element", and get a reasonable result, which is in good agreement with analytic solutions in the stress calculation as a result of fault slip..
Key words: Finite element method      Reduced element stiffness      Shear modulus      Transverse isotropic      Wounded element

 图 1 计算采用的含有断层的模型 Fig. 1 Calculation model which contains fault

 图 2 文献[1]单元降刚以后计算的位移和应力 (a)x方向(垂直于断层)的位移Ux；(b)y方向(平行于断层)位移Uy；(c)剪应力σxy(d)正应力σxx. Fig. 2 The displacement and stress distribution after reducing the Yong'S modulus of fault elements with the method used in Ref. [1] (a) Displacement Ux of the direction x(vertical to the fault); (b) Displacement Uy of the direction y(parallel to the fault); (c) Shear stress σxy; (d) Normal stressσxy.
 图 3 文献[1]单元降刚以后计算断层发生后与发生前位移和应力变化量 (a) △Ux；(b)△Uy；(c)△σxy；(d)σxx. Fig. 3 The change of displacement and stress before and after fracture with the method used in Ref.[1]
 图 4 Okata解析解计算的地震发生后位移和应力变化量 (a)△Ux；(b)△Uy；(c)△σxy；(d)△σxx. Fig. 4 The change of displacement and stress before and after fracture with the Okada's analytical solution

 图 5 横向各向同性材料图示和本构关系方程(注意其中的，因此只有5个独立参量) Fig. 5 The sketch of the transverse isotropic materialand theconstitutive relation in which SO that there is only 5 independent parameter.

 图 6 用横向各向同性介质消减G21模拟断层滑动的计算结果 (a)Ux；(b)Uy；(c)σxy；(d)σxx. Fig. 6 The result of simulation fault slipping with the method of reducing G21 in the transverse isotropic material
 图 7 横向各向同性介质消减G21模拟断层滑动的计算结果 (a)△Ux；(b)△Uy；(c)σxy；(d)σxx. Fig. 7 The result of simulation fault slipping with the method of reducing G21 in the transverse isotropic material

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