Study On Surface Movement And Deformation Law Of Fully-mechanized Caving Mining With Large Mining Depth In Chenjiagou Coal Mine

The eight mining area of Chenjiagou Coal Mine has special geological mining conditions.The mining coal seam belongs to extra-thick coal seam,which adopts fully-mechanized caving method,and there are a large number of villages and construction facilities on the surface of the mining area.Therefore,it is important application value to study the law of surface movement and deformation in Chenjiagou fully mechanized caving mining.In order to study the law of surface movement and deformation in fully mechanized top coal caving with large mining depth,based on the observation data of surface movement in fully mechanized caving face of 8512 and 8513 in the eight coal mining area of Chenjiagou Coal Mine,the law of surface movement and deformation in mining under two fully-mechanized caving face On this basis,the probability integral method is used to construct the prediction model,and the observed data is used to compare and fit the modified model parameters,and the probability integral prediction parameters under this condition are obtained,and the law of surface movement and deformation under full mining conditions is studied.Through the fitting and correction of observation data,the predicted parameters of probability integral are obtained as follows:subsidence coefficient ?=0.45,tangent value of main influence angle Tan ?=1.79,horizontal movement coefficient b=0.3,inflection point offset S/H=0.05,and main angle parameters.The results show that when the width depth ratio of working face is 0.24,the surface belongs to the state of insufficient mining;when the ratio of width to depth is 0.48,the surface belongs to the state of insufficient mining;when the ratio of width to depth of working face is 0.96,the surface is close to the state of full mining,and the surface experiences the state of extremely insufficient insufficient full mining In the process of development,the subsidence basin developed from "V-shape" to "bowl type";the surface movement increased rapidly and the angle of subsidence basin changed greatly in the process of insufficient mining development.The angle of surface subsidence basin changed little and the maximum subsidence angle gradually approached 900 in the process of fully mining development.Based on the key stratum theory and 3DEC numerical simulation method,the relationship between the fracture instability of key stratum and the surface movement after mining in multiple working faces is simulated.The results show that:when the width to depth ratio of working face is 0.24,the strata below sub key stratum 2 are all fractured,and sub key stratum 2 plays a role in controlling the subsidence of overburden,but the strata above sub key stratum 2 will appear layer separation structure in the process of movement,and the amount of subsidence developed to the surface is less than that of sub key stratum 2;when the width depth ratio of working face is 0.48,the key layer is broken,the structure is unstable,and the surface When the width depth ratio of working face is 0.96,the separation layer between the sub key stratum 2 of overburden and its underlying rock layer is closed,and the hinged structure of sub key stratum 2 develops laterally,and it will not continue to sink until it is fully compacted.The research results have important application value for "three under"mining in Chenjiagou coal mine.