Surface subsidence control during bag filling mining of super high-water content material in the Handan mining area

This paper focuses on the analysis of the overburden strata control mechanisms in stopes utilising bag filling mining super high-water content material. The factors affecting the mining-induced surface subsidence were determined, and control methods were applied to improve the filling rates of the working faces. The effects of filling rate changes on overburden failure and surface subsidence were investigated quantitatively using the field data. The results indicate that high filling rates and small changes could improve surface subsidence control. When the filling rate exceeded 86%, a 1% increase in the filling rate could decrease the average surface subsidence speed and distance by 5% and 7%, respectively. According to the current geological conditions of the Handan mining area, surface subsidence was observed as 260 mm at a 92% filling rate. Thus, these surface movements and damage indicators could be used to meet the requirements of I-level building codes and adequately control surface subsidence.