Study on the prediction model of the surface dynamic movement and deformation based on improved Knothe time function

ZHANG Zhongjie; CHEN Zhennan; LIU Jiangbin; MA Zitao; YAN Weitao; CHEN Junjie

doi:10.16186/j.cnki.1673-9787.2022120036

Abstract：Objectives In order to further explore the dynamic movement and deformation characteristics of the surface,and to deepen the understanding of the basic law of mining subsidence so as to better serve the safety and green production of mines,Methods in view of the defect of the original Knothe time function model to express the law of the surface subsidence and its velocity change,based on the dynamic formation mechanism of the surface subsidence basin during mining,the influence law of time function parameter c on the surface subsidence,subsidence velocity and subsidence acceleration was analyzed theoretically.When the subsidence velocity reached the maximum,the dynamic movement and deformation of the surface were divided into two stages,and the Knothe time function model was further improved.On this basis,the predic-tion models of dynamic subsidence,inclination and curvature movement and deformation of the surface were established.Taking 2201 mining face of a mine as an example,the prediction and accuracy of movement and deformation were analyzed.Results The results showed that,the shape of the improved Knothe time function was consistent with the dynamic movement and deformation of the surface in mining subsidence,it could better describe the whole process of"stability→change→stability"dynamic evolution of mining surface.The time function parameter c was an important parameter of the function model,which was related to geological mining conditions such as overburden mechanical properties,mining conditions and mining speed,and it was sensitive to describe dynamic surface movement and deformation,the subsidence value and subsidence velocity increased sharply with the increase of parameter c.By using the improved Knothe time function pre-diction model,the error of the predicted surface subsidence value was centimeter-level accuracy,the error of the tilt value was within 5 mm/m,the error of the curvature was within 0.7 mm/m2,and the relative error was within 6.0%.The predicted results were in good agreement with the measured results.Conclusions The prediction model had certain reliability and practicability,the law of the whole process of dynamic move-ment and deformation of the surface could be analyzed more accurately,and reference could be provided for mining under"three body"and coal pillar protection.