| As an important pillar industry of China’s national economy,coal directly affects the healthy development of the national economy.In order to solve the problem of the destruction of the adjacent roadway in the mining face during the mining stage,according to the physical and mechanical characteristics of the thick and hard roof in the 11123 fully mechanized mining face of Pan 2 Coal Mine,the mechanism and parameters of the thick and hard roof cutting and pressure relief roadway protection are studied.The purpose of this paper is to form the technology of last mining top cutting and roadway protection in coal mining face,and reduce the influence of working face recovery on adjacent roadways in the mining area,based on the research on the relevant ground pressure manifestation laws before and after presplitting and pressure relief of coal mining face,different presplitting and roof cutting layers,and through the optimization design and research on presplitting and pressure relief drilling and blasting parameters of advanced deep hole presplitting and roof cutting.The above research results are as follows:1.The movement law of overlying strata and the influence of dynamic pressure on the adjacent roadway after the mining of the working face are analyzed.When the working face starts to advance from the cut to the stop line,the curve of the advance bearing stress of the working face presents a trend of rapid rise first and then slow decline;The mining influence range of floor is obviously smaller than that of roof and coal seam,and the peak stress of floor is smaller than that of roof and coal seam;Compared with the surrounding rock of the floor roadway,the surrounding rock of the roof roadway changes more and the damage is more obvious,whether it is the scope of the plastic zone or the size of the separation value.2.Through the simulation test of A3 coal seam in 11123 working face of Pan 2Coal Mine as a similar material,according to the line ratio of the similar theoretical model,the mining height of 3# coal seam is 5.5m,which can be obtained that the height of the direct roof caving is about 10.5m,the height of the caving zone is about22.3m,the height of the fracture zone is about 46.5m,and the height of the bending subsidence zone is about 116 m.The height of the two zones measured in the experiment is consistent with the theoretical calculation,which shows that the research of this similar material simulation experiment is reasonable.3.Compared with the working condition without roof cutting,the peak value of vertical stress on the measuring line of coal and rock body is far away from the stop line,and the vertical stress distribution on the measuring line is dispersed;With the increase of the vertical height of blasting top cutting pressure relief from 10 to 57 m,the peak value of the vertical stress on the roof measuring line generally has an increasing trend,and the influence range of the leading bearing stress of the working face decreases with the increase of the blasting top cutting height.4.The blasting roof cutting and pressure relief can effectively control the deformation of the adjacent roadway in front of the working face.Compared with the displacement of the roadway under the working condition after roof cutting,the deformation of the surrounding rock of the roadway without roof cutting is large due to the influence of the advance bearing pressure;With the increase of the vertical height of blasting roof cutting and pressure relief from 10 to 57 m,the roof and floor of the adjacent roadway are greatly affected by mining,while the two sides are basically not affected by the mining of the right working face.5.Based on the optimization design of the parameters of the pre splitting and top cutting blasting hole spacing in 11123 working face of Pan 2 Coal Mine,the blasting effects under six different blasting hole spacing were simulated.Through the propagation law of blasting stress wave and the final situation of crack propagation,the optimal blasting hole spacing for the top cutting blasting in the final mining stage was determined to be 50 mm.6.Industrial tests were carried out on 11123 working face of Pan 2 Coal Mine,and blasting parameters such as technical scheme of caving,caving height,blast hole angle,blast hole depth and blast hole spacing were designed,and blasting parameters were optimized and adjusted.Figure [53] Table [17] Reference [64]... |
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