APPLICATION OF EXTEND FINITE ELEMENT METHOD TO ROCK FRACTURE MECHANICS

Rock crack propagation cannot be simulated with conventional finite element method because it is a classic discontinuity problem. Extended finite element method(XFEM)can implement the mutual independence of computational grid and discontinuity. So there is no need to re-mesh the grid model for moving discontinuity simulation. This paper introduces the basic principles of XFEM and universal criterion for rock fracture mechanics. It utilizes XFEM to simulate I mode and II mode fracture in three-point bending test as well as the double-crack shear fracture test. All the obtained results indicate that using XFEM to simulate rock fracture cannot be restrained by mesh generation and the cracks propagate randomly according to the actual stress distribution. The whole process of micro crack generation and evolution until the final total destruction of rock can be directly observed, which have great agreement with laboratory test results. This method has demonstrated its ability to investigate rock fracture mechanics and to simulate rock macroscopic and microscopic fracture process. It provides a convenient way for complex issues solution.