Simulation of role of decollement slope and surface slope angles to the stress field in accretionary wedge

摘要

The purpose of this study is to estimate the effect of surface slope-angle (α), decollement slope-angle (β) and boundary condition to the stress field within accretionary wedge by using finite element method (FEM). We impose four types of boundary conditions along the base of four types of models. These boundary conditions are expressed by liner, quadratic (convex and concave) and cubic function. Four types of models have different decollement slope and surface slope.Comparing with two models (models B and C) which have different decollement slopeangle (β), the decollement slope-angle (β) affect weakly to stress field. On the other hand, comparing with the other two models (models A and C) which have different surface slopeangle (α), the surface slope-angle (α) affects fairly to stress field. Failure area propagates wider to the tip of model as the surface slope-angle (α) becomes gentler. However the more effective factor to decide the propagation of failure area is the difference of boundary conditions. Each boundary condition has different tendency of propagation of failure area. The most widely spread failure area is calculated under the boundary condition 3 and followed in the order of boundary condition 2, 1 and 4.