Analysis on the Improved Time Function Model of Surface Subsidence

The surface subsidence process induced by underground coal mining is a dynamic process, but the existing time function models can’t reflect the regularity of surface subsidence with time properly. By investigating the whole development process of subsidence, subsidence velocity and subsidence acceleration with time, a new time function model is presented that takes the dynamic characteristics into account. The model is a nonlinear equation with multiple parameters, which are related to the final value of surface subsidence, the properties of the overburdened rock mass, mining speed, mining depth, etc. Two solutions, the two-step approach and the one-step approach, are put forward to solve the parameters. Data analysis demonstrates that the two-step approach is a highly effective method and has higher forecasting accuracy. The model’s rationality had been verified through project case. The calculated results from the improved time function model were compared with the prediction results of the existing time function models. The results indicate that the improved time function model is far superior to the existing time function models.