Research on surface subsidence velocity and influencing factors by coal mining under thick loose layers and thin bedrock

To study the law of surface subsidence velocity caused by coal seam mining under thick and loose layers and thin bedrock, taking the 110801 first mining face of a mine in Huainan Mining Area as the engineering background, the finite difference software FLAC^3D was used to simulate the surface subsidence velocity of coal mining under the conditions of different mining speed, mining height, mining width, loose layer thickness and bedrock layer thickness conditions, and the influence mechanism and sensitivity of various parameters on the surface subsidence velocity were obtained. The results indicate that: the surface subsidence velocity increases with the increase of mining speed, mining height and mining width, but decreases with the increase of foundation rock thickness and loose layer thickness; the maximum surface subsidence velocity increases linearly with the increase of mining speed, mining height and mining width, and decreases linearly with the increase of loose layer thickness, which decreases in power function with the thickness of bedrock layer; the sensitivity of each influencing factor to the maximum surface subsidence velocity is mining width, bedrock layer thickness, loose layer thickness, mining speed and mining height in descending order.