巴西构造应力场的遗传有限单元法反演

GENETIC ALGORITHM-FINITE ELEMENT INVERSION OF STRESS FIELD OF BRAZIL

基于观测的主应力方位资料，应用遗传有限单元法对巴西及邻区边界位移和板内力源进行了反演，确认了前人的研究结果：板块边界作用是控制区域应力场的主要因素，山脉和海岸地形造成的扩展力是控制应力场的一个重要因素．同时显示了板块在垂直载荷下的弯曲对局部水平应力场造成相当的影响．反演结果也表明，除了过去公认的东西向挤压作用外，巴西还受到相当明显的南北向构造作用．它的存在与最近ＧＰＳ资料的分析是一致的．研究还表明遗传有限单元法是偏微分方程反演问题求解的一种有效方法．

Based on the data of stresses orientation observed in Brazil, genetic algorithms-finite element method (GA-FEW)is applied to inverse the plate boundary displacement and nodal forces within the plate. The inversion confirms that plate boundary actions are main factors controlling the regional stress field, and spreading forces of mountains and seashores are another important factor. The inversion further shows that vertical loading on plate can produce significant affects on horizontal stresses. In addition to the well-known East-west compression, it is found that a north south compression also exists in western Brazil, in agreement with recent GPS observations. The results show that GA-FEM is an effective way to solve inverse problems of partial differential equations.