层状介质中膨胀圆台体震源模型的应力场、应变场及位移场计算

用两层介质中存在的一膨胀圆台体作为模型以便模拟地幔物质上涌孕震的力源模式．计算了层状介质结构条件下结构底部膨胀圆台模拟力源在不同横向、纵向尺度以及不同锥角时的应力场、应变场及位移场的变化．结果表明，介质中及地表附近的应力场、应变场、位移场不仅与上涌力源的几何参数和物理参数有关，而且也受到层状介质结构参数的制约和影响．这种数值模拟不仅为解释上地幔物质向地壳下部侵入的现象提供了一种有意义的方法，而且表明对于考虑地幔物质上涌孕震过程有关的前兆场分布而言，必须认真考虑介质结构不均匀性问题．

THE CALCULATION OF STRESS AND STRAIN AS WELL AS DISPLACEMENT VARIATIONS OF THE SOURCE MODEL WHICH IS A DILATANCY CONE CYLINDER BODY IN LAYERED MEDIUM

A kind of mechanical source pattern of upwelling mantle material in the processof earthquake preparation is simulated by taking a dilatancy cone cylinder bodyin two layer medium as a model.The variations of stress and strain as well as displacement in the medium are calculated when the analogous mechanical source of the cone cylinder body changes in different lateral and lengthwise scales as well as taper angle under the condition of layered medium.The results show that the fields of stress and strain as well as displacement in the medium or near the ground surface relate not only to the geometric and physical parameters of upwelling mechanical source,but also to the geometric parameters of layered medium structure.This numerical simulation provides a significant method for explaining why the upper mantle material flows into lower crust and show that the variation of medium structure must be considered for recognizing the distribution of precursor fields related to this kind of seismogenic process.