Numerical simulation study on the seepage characteristics of coal seam infusion effected by mining-induced stress

Mining-induced stress will cause the change of coal seam pore structure. However, most coal seam infusion simulation studies do not consider the change of pore with mining-induced stress. In order to study the impact of mining-induced stress on coal seam infusion, this paper used the triaxial compression test of coal as the basis to establish the relationship equation between volume strain and stress loading by the volume deformation table, and then introduced the relationship equation into FLUENT through Fluent Custom Function (UDF). Taking the mining time and water injection time as the axis, this paper compared and analyzed the variation law of coal seam infusion seepage parameters with coal seams with pore changes caused by mining-induced stress (model I) and traditional fixed porosity (model II). The results show that in the elastic deformation stage, the mining-induced stress makes the original pores of the coal seam compact, so that the water injection seepage pressure, seepage velocity, and water content volume of model I are lower than those of model II. In the plastic deformation and post-peak deformation stages, mining-induced stress promotes the development of coal seam pores, and the water injection seepage pressure, seepage velocity, and water content of model I gradually exceed the seepage field parameters of model II. It can be seen that mining-induced stress has an important impact on water injection seepage. The simulation method proposed in this paper can more truly reflect the impact of actual mining process on coal seam infusion seepage.

Automated summary

The study revealed that mining-induced stress has a significant impact on the pore structure of coal seams and infusion seepage parameters, influencing the extent of pore opening and the permeability of water injection. The proposed research method can more accurately reflect the impact of coal seam mining on infusion seepage.