基于准三维有限元方法建立的地震活动模型

A SEISMICITY MODEL BASED ON PSEUDO 3D FINITE ELEMENT METHOD

基于有限元方法 ,参照细胞自动机模型 ,建立了一个地震活动演化的动力学模型 .在这个模型中 ,根据边界条件和单元介质参数的分布 ,利用有限元方法确定各单元的应力增长速率 .每个单元设定初始应力和摩擦因数 ,利用破裂准则可得到单元破裂所需时间 .当单元破裂后 ,将破裂单元作为内部边界 ,利用有限元方法计算由于这个单元破裂对系统其他单元造成的应力调整 .根据上述规则 ,建立一个由 3 0× 40个节点组成 ,在定常位移速率边界条件作用下的地震活动模型 ,探讨了区域应力场的动态演化、地震活动图像和各种参数变化对地震活动的影响 .结果表明该模型在研究地震活动方面有一定优势并具有实用价值 .

A dynamic model of seismicity evolution is built based on finite element method according to cell automation model. In the model, the stress increase rate of each cell is obtained by boundary condition and cell medium parameter distribution using finite element method. When each cell is assumed as definite initial stress and frictional coefficient, the broken time of each cell is determined by breaking rule. After a cell is broken, the stress adjustments of the other cells in the system are obtained by finite element method using the broken cell as inner boundary. According the above rules, the seismicity model with 30×40 points is built under the condition of constant displacement rate. The dynamic evolution of the regional stress field, seismicity patterns and effects of various parameter changes on seismicity are discussed. The model presented in this paper shows some advantages and practical usefulness in seismicity research.