Seismic Response of Artificial Dams in Coal Mine Underground Reservoirs

Coal mine underground reservoirs are increasingly used for mine-water storage and reuse in ecologically fragile mining regions, but the dynamic response of artificial dam structures under coupled water-pressure and seismic loading remains insufficiently understood. This study develops a simplified two-dimensional frame-based dynamic model to compare flat slab, gravity, and arch-equivalent artificial dams. Two water pressure levels, 0.1 and 1.0 MPa, and two seismic intensities, PGA = 0.1 g and 0.5 g, were considered using four representative acceleration histories. The arch dam was represented by a vertical rectangular section with equivalent arch-action lateral restraint. Results show that water pressure primarily controls peak total displacement, whereas PGA mainly governs the dynamic displacement increment and absolute acceleration. Increasing water pressure from 0.1 to 1.0 MPa markedly amplified total displacement and tensile stress demand, while increasing PGA from 0.1 g to 0.5 g produced a clearer effect on dynamic increments than on total displacement. The arch-equivalent dam consistently showed the smallest displacement response, while the gravity-type dam developed higher tensile stress demand under high water pressure in the simplified model. Effective modal frequencies were relatively high, explaining the coexistence of small displacement demand and noticeable acceleration response. The results provide a mechanistic basis for artificial dam-type comparison and preliminary safety assessment in underground reservoirs.