The Establishment And Application Research Of Dynamic Subsidence Prediction Model Based On Normal Time Function

In recent years,the continuous mining of coal resources has formed a large number of mined-out areas,which has caused various forms of damage to the surface,including landslides,ground cracks,collapse pits,etc.At the same time,the mining has caused different degrees of damage to the structures above the mined-out area,leading to the sharp contradiction between the miners and the surrounding residents.Traditional solution is static prediction and mining subsidence in time and space is a complex process of four dimensional change.Since the static prediction cannot reflect the dynamic change,it has some defects in practical application.At this time,it is particularly important to establish the dynamic subsidence prediction model based on the dynamic movement and deformation law.The miners can take timely measures to protect the disturbed buildings and structures according to the dynamic prediction model.Time function is the core of dynamic prediction model.The traditional research object of time function is a single feature point,and the study of time parameter changes with position in the mining process is insufficient.The normal distribution time function has good space-time completeness,the velocity curve is regular and symmetrical,and the acceleration curve is consistent with the dynamic development law of surface subsidence.Based on the optimized normal time function,a dynamic subsidence prediction model dependent on position is established in this paper,and a series of research results are obtained as follows:(1)In this paper,by introducing the advancing influence distance and the lag distance of the maximum subsidence velocity,a dynamic prediction model related to the position of the whole basin is established on the basis of the optimized normal time function,and the calculation formulas of the starting moving time and duration of movement are given.The model is simple to construct and can be combined with various static prediction methods.(2)In combination with the measured data of the strike point of the working face in Datong,the change law of shape parameter C with position was explored by using the least square fitting method,and the working face in Xinzhou under different geological conditions was selected to verify the reliability of the law.The results show that the morphological parameter is a piecewise-function within the scope of the moving basin model.After the fitting parameter is substituted into the model,the mean square error is maintained between 4%-9% by comparing the time function value of observation points with the measured subsidence ratio.At the working face in Xinzhou under soft geological conditions,the mean square error of prediction is maintained in the range of1%-5%.Through processing the measured data of working face,it is found that the mean square error of the model prediction is within a reasonable range,and the overall prediction accuracy of the model is relatively stable.(3)Because two working faces are located close to each other and the geological and mining conditions are similar,the normal time function model is applied to the dynamic prediction of another working face in Datong,which can provide a reference for the mining operator in due time.In this paper,the static subsidence value obtained by the probability integral method is multiplied by the normal time function value to obtain the dynamic predicted value of each point.At the same time,it is compared with the measured value of the observation point buried above the working face in each period.The results show that the predicted subsidence value of the prediction model with normal time function is close to the measured subsidence value and the accuracy can meet the practical requirements.(4)Based on dynamic normal time function prediction model,the algorithm is designed by using MATLAB language.Based on the static subsidence value,the program can visualize the dynamic prediction results after calculation.The program has the function of drawing the subsidence map of the main section and three-dimensional subsidence basin.The dynamic normal time function prediction model can serve for the accurate prediction of dynamic surface movement and deformation in the mining area and provide important reference for the protection of buildings and structures in the mining area.