Prediction Method Of Longwall Surface Subsidence With Overburden Compaction Grouting

The overlying rock isolation grouting and filling technology has the advantages of low cost and small mining and filling interference,and is an effective means to liberate the "three under" coal pressure.When conducting a technical feasibility analysis of a mine,it is first necessary to predict the surface subsidence under the conditions of grouting and filling in the working face,taking into account the mine conditions.The results are an important basis for selecting the grouting layer and grouting amount.The existing prediction of grouting surface subsidence is mostly based on empirical values to estimate the estimated parameters,and there is a lack of a method for predicting grouting surface subsidence that takes into account the grouting layer and grouting volume.The thesis adopts a comprehensive method of theoretical derivation,model construction,program implementation,and on-site example verification to study the prediction method of surface subsidence caused by overlying rock isolation grouting filling.Firstly,a prediction method for surface subsidence caused by horizontal coal seam grouting filling in a single working face was studied,and a layer by layer prediction approach considering the grouting compaction zone was proposed.The predicted subsidence of the lower rock layer of the key layer is obtained from coal seam mining,and then the subsidence of the upper rock layer of the key layer is obtained by subtracting it from the maximum thickness of the grouting filling body.Finally,the subsidence is regarded as a virtual mining space with variable mining thickness,and other subsidence prediction indicators such as surface subsidence and horizontal deformation after grouting filling are estimated.The grouting filling body used in this model conforms to the trapezoidal distribution,and the filling boundary is approximately located directly above the mining boundary on both sides of the working face.The grouting compaction area is the maximum filling thickness area,and the filling thickness decreases linearly from the boundary of the compaction area to the boundary of the filling body.Furthermore,the prediction of grouting and filling settlement in inclined coal seam mining was proposed,and the calculation formula for the dip angle of the working face and the calculation method for the main influencing radius and other related parameters were provided.For the situation of repeated mining and grouting filling in multiple working faces,it is divided into two types: with isolated coal pillars and without isolated coal pillars.Multiple working faces with isolated coal pillars are expected to directly stack the expected results of each working face,while without isolated coal pillars,each working face is expected to be considered as a whole.In order to determine the parameters used in predicting surface subsidence in overlying rock isolation grouting filling,a parameter inversion method based on the modular method is proposed to solve the basic idea of nested modular method for two sets of predicted parameters from coal seam to grouting layer and from grouting layer to surface.Among them,the predicted parameters of the measured subsidence of the long wall surface of a similar working face from the reverse grouting layer to the surface are used as the internal circulation of the vector method;The predicted parameters from the measured subsidence of the surface of the similar working face grouting to the injection layer of the coal seam are used as the model vector method for external circulation,thus obtaining the most suitable predicted parameters for grouting surface subsidence in the mining area.This thesis contains 60 pictures,5 tables and 128 references.