Improvement of Knothe model and analysis on dynamic evolution law of strata movement in fill mining

CHEN Qingfa; NIU Wenjing; LIU Yanzhong; CHEN Qinglin; LIU Junguang; FAN Qiuyan

Abstract：Knothe time function model is the most commonly used models in the dynamic prediction of stratum movement.However,this model is incompletely consistent with the objective law of the dynamic evolution of the stratum movement.Based on the analysis of this defect,the two-parameter which represents the effect of time on function change and characterizes the nonlinear stratum movement was added and the improved Knothe time function was established.The sheet model of the bending deformation of small deflection in stratum movement when using the filling mining system was built on the basis of the elasticity theory.The improved Knothe time function model was combined with the strata movement model in the filling mining system,the functional expression of dynamic evolution of stratum movement as time goes was established and this evolutionary process was classified as the initial period,the active period and the declining period.The case analysis of the dynamic process of stratum movement in the filling system was carried out based on the measured data of backfilling method with refuse of No.2205 working face in Zhai town coal mine,Xinwen mining area.The results show that the speed of the maximum point of surface subsidence is 10.526 mm per month,the total time of stratum movement is 38.9 months,and the initial period,the active period and the declining period are 20.5 months,5.1 months and 13.3 months,respectively.It can be seen clearly that this function expression can objectively reflect the quantity of stratum subsidence,the rate of subsidence and the objective law of the change of the subsidence acceleration.