Fluid-Solid Coupling Simulation Method for Water Immersion Weakening in Coal Mining

Focused on the engineering problem of the water-rock interaction weakening in coal mining, the simulation methods of fluid solid coupling for water immersion weakening are proposed. The permeability and strength of coal-rock mass can be realized to update real-time during mining and water immersing in the methods. The implementation process of the simulation is discussed with the discrete element method as focus. And the implementation characteristics of the finite element simulation method are further discussed. The permeability is updated through stress and crack opening in the discrete element simulation method. Meanwhile, the variable joint stiffness simulation method is proposed that considers changes in crack compressibility. When the water seeps into the joint crack, the update of the water content is calculated by the change in joint opening. Before the coal-rock mass is yielded, the weakening strength is updated based on the relationship between water content and coal-rock mass strength. Compared with the discrete element simulation method, the update of the permeability is need to consider anisotropy in the finite element simulation method. The update of the saturated water content is calculated based on the porosity.