Study on surface subsidence dynamic prediction model based on variogram

Surface subsidence caused by mining of mineral resources endangers the safety of human life and property. Studying the dynamic process of surface subsidence changes with time is of great guiding significance for preventing and controlling the deformation and destruction of surface structures in goafs. In order to accurately describe the dynamic process of surface change with time caused by mining，theoretical analysis and experimental verification about mining subsidence are carried out based on the variogram theory.Based on the theoretical knowledge of probability integral method to deduce the time of surface subsidence which was put into the range of the variogram. In order to make the model conformed to the law of surface subsidence when described the subsidence，velcity and acceleration of the surface point changed with time，a model using different indices was combined with the subsidence data of the four mining areas to conduct a comparative analysis. It was found that when the model molecular index H was 4，the expected sinking time was the closest to the time calculated by probability integral method，and the denominator index K was proportional to the sinking time，so the best index of the model was:H=4，K was the value to be fitted and then a dynamic prediction model based on variogram is proposed. The result is obtained through comparison and analysis with the measured data of the working faces in the two mining areas，it is concluded that the mean square errors of the predicted subsidence quantity of the model are 0.027，0.026 and 0.039 m; the relative median errors are 1.69%，1.62% and 2.44%，and the errors of the maximum subsidence speed are 4.7%，6.1% and 8.1%;the mean square errors of the surface sinking velocity are 0.001 4,0.001 0 and 0.001 4 m/d，respetively，the relative median errors are 6.16%，4.46%，6.36%，respetively; the subsidence process changes with time of goaf surface is basically consistent with the measured subsidence process. The experimental results show that model conforms to the law of surface subsidence when it was used to describe the subsidence,velcity and acceleration and surface subsidence，and has practical value.