Dynamic Prediction Model Construction Of Overburden Strata And Surface Land Subsidence Triggered By Underground Longwall Coal Mining And Its Application

Implementation of research on prediction of coal-induced surface dynamic subsidence and optimization of parameters can significantly reduce mining damage and protect national infrastructure and safety of life and property.The thesis adopts research methods and methods combining field measurement,theoretical analysis and numerical calculation to realize the integrated dynamic prediction of overburden and surface subsidence.The paper first analyzes and discusses the existing typical time functions used to describe the dynamic prediction of subsidence,and gives three essential characteristics of an ideal time function mode:（1）The surface subsidence curve is“S”,and the Value traversal[0,1]interval;（2）The surface subsidence speed gradually increases from 0 to v_max,and then approaches 0;the surface subsidence acceleration conforms to 0→a_max→0→-a_max→0;（3）The surface subsidence velocity curve can show the change of symmetry or asymmetry（or skewness）with different time function parameters,that is to say,it can truly reflect the subsidence characteristics within the duration of surface movement（initial period,active period and declining period）.Based on this,a Logistic time function model that satisfies the characteristics of an ideal time function is constructed,its time and space completeness is demonstrated,and a method for determining the model parameters is given.Based on the probability integral method,the theory and method of fusion prediction of overburden and surface subsidence were reconstructed,and the method was combined with Logistic time function to establish a dynamic prediction function model of integrated overburden and surface subsidence.Based on the MATLAB R&D platform,the corresponding integrated subsidence dynamic prediction information system was compiled,and the quantitative prediction of movement and deformation of the mining surface and overlying rock layers was realized.Finally,with the backgrounds of Chensilou Coal Mine and Fangezhuang Coal Mine,the movement and deformation of ground and overlying rock layers induced by mining were predicted and analyzed respectively,and the correctness of the prediction model was demonstrated.The results show that the predicted maximum values of the relative median errors in the direction and trend of the 21104 working face of the Chensilou Coal Mine are±5.98%and±4.21%respectively;the estimated relative median errors of the settlement of the internal monitoring points of boreholes M₁ and M₂ are±4.0%and±7.6%,the predicted values are in good agreement with the measured values.The integrated dynamic prediction model given in this paper can achieve scientific and reasonable prediction of the dynamic subsidence of the surface and overlying rock layers.