Theory And Method Of Residual Movement And Deformation Of The Whole Basin On The Surface Of Gently Inclined Coal Seam

After the coal seam is mined,the upper rock mass collapses due to the loss of support,and the subsidence of rock mass will gradually develop to the surface and form a sinking basin on the surface.If the subsidence value of the surface for 6 consecutive months does not exceed 30mm,it is considered as standard,and the surface deformation reaches a relatively stable state.However,it is found that when the rock mass above the mining coal seam is affected by external factors such as earthquake,groundwater and additional load on the surface,the residual movement and deformation of the surface will occur.Residual movement and deformation are related to the foundation stability of surface buildings,which is not considered in current regulations.Relevant scholars have found that the residual movement deformation in some mining areas will not occur until 50 years after the end of mining.Therefore,the further research on residual movement deformation is a hot topic both in theory and simulation.In this paper,by analyzing the existing state of the mining coal face and the upper rock mass before the surface residual deformation occurs,it is found that there are voids around the boundary of mining coal face due to the existence of rock beams.Therefore,when studying the mathematical model of residual deformation in the surface subsidence basin,we should not only consider the cavity influence on both sides,but also consider the cavity influence on all sides.In this study,the working face of mining coal seam is divided into five segments,the surrounding cavity area and the middle unconsolidated area,to study the mathematical model of residual movement and deformation in the whole subsidence basin.By assuming the upper rock mass of mining coal seam as a random medium theoretical model,the delamination,fissures and voids existing between rock layers after rock collapse are equivalent to mining blocks with a certain thickness.The residual deformation of five segments is calculated respectively by using the superposition principle of probability integral method,and then superimposed and summed,and the theoretical system of residual movement and deformation in the whole basin of gently inclined coal seam mining is constructed completely for the first time,including the mathematical models of residual subsidence,residual inclination,residual curvature,residual distortion,residual horizontal movement and residual horizontal deformation.With the mixed programming of Visual Basic and Matrix VB,the deduced formula of residual deformation series is written as a program,and the parameters of rock movement in actual engineering mining are input into the prediction program,and the three-dimensional curved surface and two-dimensional curve of residual deformation are obtained.By comparing the predicted results of the program with the observed results,the accuracy of the mathematical model established in this paper is verified.Based on the actual geological data,FLAC^3Dnumerical model is established,and through qualitative analysis of numerical simulation,the correctness of deformation form of rock mass in the analysis of residual deformation mechanism in this paper is verified.Through example verification and numerical simulation analysis,it showed that the prediction theory and the program in this paper can quantitatively analyze practical engineering problems,and have strong generalization.