A Numerical Simulating Study of Mechanical Characteristics of Superposed Deformation in Daba Mountain Foreland

In this article, the mechanical characteristics, the interference patterns of superposed folds, and the feature of united arc-shaped structure in Daba mountain foreland are studied using nonlinear finite element numerical method. In addition, the developed procedure of a series of arc-shaped structure with time is demonstrated, and a group of boundary conditions adapted to the superposed deformation in this region is obtained. The study shows the following: 1 The creep materials selected in our model are deformed greatly with time, but the variation of stress field is small and slow, which makes it possible to study the tectonic deformation through principal stress trajectory. 2 The major interference patterns of superposed folds in Daba mountain foreland are roughly perpendicular, mitred, and syntropic superpositions. 3 The formation of Daba arc-shaped structure is believed to be due to the action of northeastern boundary forces, as well as the two tectonic convergences at east and west part, but another arc-shaped structure in eastern Sichuan basin assembled with Daba mountain forming a convergent double arc is believed to be due to the action of the boundary forces from southeastern orientation.