Study on the generation of earthquake motions considering fault rupture process

在这项研究中，我们用三维有限元方法对断层破裂机制和断层上及附近的强震运动进行了参数分析。首先，我们研究了断层长度对破裂传播过程、断层面位错大小的影响，以及对地震运动的影响。并将三维分析结果与二维分析结果进行了比较。主要结果如下：(1)破裂沿初始剪应力方向快速扩展，然后破裂锋I逐渐呈同心圆形状扩展。(2)随着断层长度的增加，位错的平均幅度变大，并接近于2D结果。由三维分析得到的位错与由二维分析得到的位错之间的关系被表示为断层长宽比的函数。(3)在波形比较中，…当观测点在断层上时，3D分析得到的波形与D分析得到的波形的幅值和相位吻合较好，但随着距离断层距离的增大，两者之间的差异增大。其次，利用三维有限元方法模拟了2000年10月6日托托里肯-西武地震的断层破裂过程和加速度记录。我们分析了两种情况，即情况1，断层上的应力降分布是恒定的，情况2，其分布与通过反演分析得到的情况相似。研究了位错的破裂过程和破裂幅度，并将模拟的加速度与记录的加速度进行了比较。我们发现位错是可重现的，但需要考虑地面条件、风帆的非线性特性等因素来模拟加速度记录。第三，开发了三维模拟的前置处理和后置处理，并利用非线性三维有限元方法构建了在线模拟器。借助该系统的周转时间，从语法上减少了生成用于分析处理和绘制的数据集的时间。较少

In this study, we performed parametric analyses to examine fault rupture mechanism and strong earthquake motions on and near a fault by using three dimensional (3D) finite element method. First, we examined the effect of the length of the fault on the rupture propagation process, magnitude of the dislocation on the fault plane, and generated earthquake motions. Then, the comparison between the results from 3D analyses and those from2D analyses was made. The main results were as follows;(1) The rupture propagates in the direction of the initial shear stress at fast, and then the rupture front I gradually extends in the shape of a concentric circle.(2) The average magnitude of dislocation becomes large and approaches to a 2D result as the fault length becomes long. The relationship between the dislocation obtained from the 3D analyses and those from the 2D ones was expressed as a function of the ratio of the length of the fault and the width of it.(3) In the comparison of wave forms, the … More amplitude and the phase of the waves from 3D analyses and from D ones correspond well when the observation point is just on the fault, but the difference between them becomes increases when the distance from the fault becomes large.Next, we simulated the fault rupture process and acceleration records of the 2000 Tottoriken-seibu earthquake which occurred on October 6, 2000 by 3-D FEM. We analyzed two cases, I.e., Case1, the distribution of the stress drop on the fault was constant, Case2, the distribution was similar to that one which was obtained by the inversion analysis. The rupture process and magnitude of the dislocation were examined and simulated accelerations were compared with recorded ones. We found that the dislocation was reproducible but that it was necessary to consider ground condition, nonlinear characteristics of sail, etc. to simulate acceleration records.Third, we developed a preprocessor and a post processor for the 3D simulation and constructed on-line simulator acing nonlinear 3D finite element method. By virtue of the system turn-around time to generate dataset for the analysis and processing and drawing the obtained data was grammatically reduce. Less