Simulation And Analysis Of Viscoelastic Bodies On Deep Tectonic Deformation Of The Longmen Shan Fault Zone

At 2:28p.m on May 12th 2008, the great earthquake took on the Longmen Shan fault in Sichuan province. The earthquake caused huge casualties and economic loss. The Wenchuan earthquake occurred on the Longmen Shan fault belt which is between the stabile Sichuan Basin and the Qinghai-Tibet plateau having a complex geological structure. And the region's surface slip rate is lesser. So the region has been considered "calm" area of the earthquake. Therefore, sudden and strength of the great earthquake gave a surprise to scientists and brought a huge doubt that how did the huge energy accumulate to trigger the great Wenchuan earthquake while the rate of superficial tectonic deformation was very lower? Therefore, the great earthquake made us the new thinking of establishment of dynamics theory model and study.We got an inspiration from the Wenchuan earthquake that low slip rate on surface of the fault zone doesn't mean weak seismicity. Although the surface deformation of Longmen region is lesser, but the area of geological structure is complex and its deformation situation of depth has not been studied, maybe slip rate of the region deep is the main factors which cause the earthquake. According to the Longmen mountain fault's characteristic, we developed a geological model in the Tibet plateau and took the viscoelastic contact analysis method to make an analysis research on the stress distribution and tectonic deformation of the Longmen Shan fault zone, and got the following research:(1) Develop a geological model on research objects with the finite element analysis program ANSYS. Considering the geological structure of particularity and complexity in the Longmen mountain fault zone, the model would involve as far as possible big regional in the length and depth.(2) Define the upper crust and of the model as elastic area, the lower crust and upper mantle as viscoelastic materials area and exert contact constraint between the crust and the crust and t upper mantle.(3) Use the finite element program to simulate and analyze the stress distribution of the Longmen mountain fault zone and its surrounding areas in the process of flow east of the Tibet plateau substances.(4) Based on numerical simulation, inspect slip displacement conditions of the Longmen Shan fault and make analysis on slip rate of the model to explore potential factors of the Wenchuan Earthquake in the case of superficial deformation rate lesser.Through the finite element research on Longmen Shan fault region, the model results have theoretical and practical analysis significance. Considering the deep tectonic characteristics of the Longmen Shan and the activity of the fault and physical mechanism of the Tibet plateau migration, discuss dynamics mechanism of the Wenchuan Earthquake.