Critical Instability and Dynamic Loading Laws of the Artificial Dam in the Coal Mine Underground Reservoir

Abstract

Establishing underground reservoirs in coal mines to protect water resources has become a new option. Ensuring the stability of an artificial dam is crucial for the safe operation of underground water reservoirs. Therefore, this paper takes the Daliuta coal mine as the background and first establishes a thin plate model for the fracture mechanics of the artificial dam based on Galerkin method to determine the deflection-stress relationship equation. Based on the Drucker-Prager criterion, the yield function of the inner and outer surfaces of the artificial dam body is established to determine the maximum water level that the artificial dam can withstand. Subsequently, a numerical model is created based on the obtained results to analyze the velocity, displacement, and stress change patterns of the artificial dam body at different locations under dynamic loading. The study results indicate that the destabilization of the dam occurs in the following order: top and bottom edges of the inner surface, side edges of the inner surface, and center of the outer surface, leading to destabilization of the dam at a limiting water level of 31.6 m. Numerical simulation supports the conclusion that given the same impact intensity, a closer distance to the earthquake source results in a larger corresponding horizontal displacement. The velocity curve is divided into three phases: impact compression zone, energy attenuation zone, and turbulence reflection zone. The stress manifests itself in the fact that given the increase in the dynamic load intensity, the concentration of the stress gradually shifts to both sides of the dam body and the top and bottom plate rock layers. The stress value in the elastic zone around the dam body increases from approximately 5 MPa to 12.5 MPa given a dynamic load strength of 20 MPa.