Seismic performance analysis of flat artificial dam of underground reservoir in coal mine

The coal mine underground reservoir effectively solves the problem of mine water protection and utilization in the western mining area. The safety and stability of the underground reservoir is the key to the implementation of the core technology of “guiding, storing and using”,and the artificial dam is the link connecting the reservoir dam. Therefore, aiming at the safety and stability of the artificial dam of coal mine underground reservoir, using the typical flat artificial dam as the research object, based on the basic situation of the Daliuta 2^-2 coal mine underground reservoir, the stability characteristics of the flat artificial dam of coal mine underground reservoir under different earthquakes(1-15 m/s²)are analyzed in this study by using the research methods of similar simulation experiment and numerical analysis. The similar simulation results show that the flat artificial dam of coal mine underground reservoir can resist earthquakes above 10 degrees(12 m/s²),and the maximum displacement under cyclic loading from small to large earthquakes is 0.19 mm. The stress concentration position of the artificial dam body is mainly at the bottom of the dam body, and the stress variation law is bottom > middle > top. Under the action of the same seismic wave, the peak stress on the reverse side of the dam body is about 10% greater than that on the front. There is no crack development in the artificial dam body during the whole vibration process, indicating that the artificial dam body always maintains an elastic working state. During the gradual increase of top pressure and cyclic earthquake, the internal stress of the artificial dam increases sharply, but the horizontal displacement of the dam is equivalent to that in the non-pressurization stage, and there is no obvious increase. However, the coal pillar dam gradually produces some cracks in this process, and finally the cracks are connected, resulting in the collapse and failure of the coal pillar dam. On the whole, the underground reservoir dam body(coal pillar + artificial)of the Daliuta 2^-2 coal mine does not have large plastic deformation under the action of earthquake, and the displacement change is the largest in the direction perpendicular to the roadway, but the variation range is mm scale. The reservoir dam body maintains a good stability under the action of earthquake. Due to the different materials(strength and density)of artificial dam and coal pillar dam and the different acceleration caused by vibration, the acceleration of artificial dam is greater than that of coal pillar dam, resulting in the concentration of shear stress at the dam connection, which is the key position prone to damage of coal mine underground reservoir.