Discrete element numerical simulation of triaxial fluid solid coupling based on seepage experiment

Abstract

The coupling characteristics of coal seam stress,fracture and seepage directly affect the migration characteristics of pressure relief gas during the protective seam mining.In this paper,combined with cubic law,the method for the selection of the fluid solid coupling parameters of elastic joints and persistent fracture was proposed based on the experimental data of the elastic and persistent fracture coal samples.Meanwhile,the simulation modeling of fluid solid coupling for triaxial flow test of coal samples was built.On the basis of this simulation method,the coupling characteristics of the coal sample stress,fracture and flow were simulated and analyzed during uniaxial and triaxial loading.The simulation results show that the permeability of coal samples changes as S type with the increase of axial strain.The permeability of coal sample decreases gradually with the increase of axial pressure before the fracture of coal sample development.The permeability of the coal samples increases with the development of the fractures,and the faster the fracture expansion rate is,the higher the permeability increases.The increase of confining pressure resulted in the decrease of internal fracture generation and propagation,and the permeability reduction stage was extended.The initial permeability and yielding permeability of the coal samples decreased gradually.

Keywords

• numerical simulation
• seepage characteristics
• stress sensitivity
• laboratory measurement
• persistent fracture