Simulation Of Hydraulic Fracturing Of Rock Mass Due To High Water Pressure By Using Element-Free Method

Groundwater deposit in the cracks of rock mass. Its hydraulic pressure on the crack surfaces makes the intrinsic cracks or flaws appear propagation and perforation, that is hydraulic fracturing. Hydraulic fracturing is one of the important influence factors of stability of rocks mass and the project buildings upon the rock mass in the rock projects with wicked hydro-geological conditions, such as high water pressure and deep burying.Along with the development of society, lots of heavy constructions are developing to the underground, underground engineering can't separate with the force of groundwater, all of these promote the development of hydraulic fracturing research. The hydraulic fracturing of rock mass is one embranchment of the fissured rock mass seepage-stress coupling research. Up to now study on this problem is just in its initial stage, lots of basic theoretical problems should be researched more deeply.Firstly, the fundamental theories of Moving Least Squares Method(MLSM) which is the basic theory of EFM are studied. Based on this, the basic equations of EFM are derived, solving equations with Conjugate Gradients Method. Numerical examples show that EFM simplifies pre- and post-processing and can solve problems with higher accuracy.Then, the double mechanical effects of fracture flow is studied. The form and exertion of hydrostatic pressure and hydrodynamic pressure on the cracks surface is studied, and consider the influence on the stress filed, strain filed and displacement filed in the area of cracks tip and the consequent displacement of rock mass , as wellas the propagation of cracks fracturing.Last, combining with the theory of facture mechanics, study on the application of element-free method to simulate hydraulic fracturing is presented due to the advantage of using element-free method to simulate crack propagation. The stress intensity factor of complex fracturing is calculated using modified J integral and an element-free program for the simulation of hydraulic fracturing is complied. Numerical examples show that the element-free program tracing crack propagation has a good description of the track of crack propagation.