应用非连续模型研究断层对地壳应力的影响

Effects of faults on crustal stress using discontinuous model

通过有限元数值模拟的方法,应用非连续的接触模型研究断层对地壳应力的影响。研究结果表明:非连续模型比连续模型能够更好地模拟断层,突出了断层对地壳应力的影响作用,避免了单纯使用软弱带模拟断层所导致的应力削弱现象;非连续模型通过接触单元可以描述连续模型所不能反映的断层带与围岩之间的不连续错动;断层端部和复合断层交叉处附近是应力集中区;断层带具有较高的剪切应力,但其自身及附近局部区域的最大主应力受到了一定的弱化;断层的弹性模量、断层与区域主应力的夹角以及交叉断层是地壳应力的重要影响因素,平行断层是弱影响因素,断层泊松比对地壳应力的影响不大。

The effects of faults on crustal stress applying discontinuous contact model were studied through FEM numerical simulation.The results show that discontinuous model is better than continuous model in modeling faults,and it highlights the influencing effect of faults on crustal stress and improves stress-weaking resulting from simply modeling faults with weak-belts.The discontinuous dislocation between fault belt and surrounding rock can be depicted by discontinuous model rather than continuous model.The ends of faults and the vicinity of the cross of complex faults are stress concentrational region.The shear stress in fault belt is high but the maximum principal stress near faults in itself is weakened to some degrees.The elastic modulus of faults,the angle between faults strike and regional maximum principal stress and intersectant faults are important influencing factors for crustal stress.Parallel faults are weak factor.The poisson ratio has little influence on crustal stress.