Numerical analysis of overburden soil subjected to strike-slip fault: Distinct element analysis of Nojima fault
Numerical analysis of overburden soil subjected to strike-slip fault: Distinct element analysis of Nojima fault
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走滑断层覆盖土的数值分析：野岛断层的离散元分析
DOI：
10.1016/j.enggeo.2011.08.003
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
H. Taniyama
中科院分区：
文献类型：
--
作者：
H. Taniyama
采用离散元法分析了走滑断层作用下覆岩剪切带的发展规律。在分析中使用了大约230万个球形粒子，并将结果与1995年兵库县南部地震期间在野岛地震断层上观测到的剪切进行了比较。在数值分析中观察到了雁列剪切和次级剪切，它们以较低的角度与基底断层（典型的走滑断层）相交。水平面内的简单剪切和由于速度对深度的依赖而产生的阻力被证实控制了里德尔剪切的螺旋形状。由于沿沿着里德尔剪切带的滑动，挤压方向向断层走向的旋转也得到了证实。据发现，压缩方向是更水平的里德尔剪切比在外部地区所包围的区域内，这些压缩方向产生次级低角度剪切，是螺旋形。结果表明，柱状结构的颗粒和随后的屈曲的形成发挥显着的微观力学的作用，在三维剪切。数值分析的结果，如剪切间隔和冲击角，显示出类似的观测结果，在网站的沉积物含有粗颗粒，并受到走滑与小倾角分量，虽然他们是不完全相同的位置与类似的覆盖层厚度观察到的。
A distinct element method analysis is carried out to examine the development of shear bands in overburden soil subjected to a strike-slip fault. About 2.3million spherical particles are used in the analysis and the results are compared with the shears observed at the Nojima earthquake fault during the 1995 Hyogoken Nanbu earthquake. En echelon shears and secondary shears which strike at lower angles to the basement fault – typical in strike-slip faults – are observed in the numerical analysis. Simple shear in the horizontal plane and drag due to the dependence of velocity on depth are confirmed to control the helicoidal shape of Riedel shears. Rotation of the compressional direction toward the fault strike as a result of slip along Riedel shears is also verified. It is found that the compressional direction is more horizontal within the area enclosed by Riedel shears than in outside areas and that these compressional directions produce secondary lower-angle shears that are less helicoidal. It is shown that the formation of column-like structures of particles and their subsequent buckling play significant micromechanical roles in three-dimensionally wrenched shears. The results of the numerical analysis, such as shear intervals and striking angles, show a resemblance to observational results at sites where sediment contains coarse grains and is subjected to strike slip with a small dip component, although they are not exactly the same as those observed at locations with similar overburden thicknesses.