Research On Bolt Support Optimization Of 4^-2 Coal Seam Coal Roadway In Zhangjiamao Coal Mine

The condition of shallow coal seam in the northern Shaanxi mining area is good,and the bolt support has a relatively rich coefficient in this area.At present,the cost of support is high.Taking the 14204 working face of the 4-2 coal seam of Zhangjiamao coal mine as the research background.Based on the comprehensive analysis method,including the field measurement,physical simulation,numerical calculation and theoretical analysis,in order to optimize the bolt support parameters of the 4-2 coal seam coal roadway and provide theoretical guidance and practical value for production practice.Through the site acquisition of rock samples and laboratory measurements,the basic physical and mechanical parameters of the 4-2 coal seam of Zhangjiamao Coal Mine were obtained.According to the results of roof stability classification,the 4-2 coal seam roof is a type II.The roadway of convergence and surface observation results show that: within 53 m from the mining face,with the advancement of the working surface,the cumulative deformation of the two sides of the rubber transport groove and the cumulative subsidence of the roof continue to increase.However,the measurement point of the auxiliary transport along the trough is about 30 m behind the goaf of the working face,which is greatly increased by the advance pressure.Based on the observation results of the loosening circle of the auxiliary transport along the mining process,it is concluded that when the mining face is 20 m away from the monitoring section,the surrounding area of the roof rock increased;when the mining face is-63 m from the monitoring section,there is obvious breakage 0.5~1 m from orifice,and there is a certain amount of breakage in the roof hole;when the mining face is-93 m away from the monitoring section,the crushing area is significantly larger than before,and rib spalling is severely broken.Based on the monitoring results of convergence along the gateway,the results of monitoring the separation of the roof and the monitoring results of the loosening zone of thesurrounding rock,the bolt support theory was used to optimize the existing bolt size and support strength.Using ANANYS simulation,it is found that the dish-shaped straight edge tray,not only can meet the requirements of deformation and stress.The size of the dish-shaped straight edge tray is 120×120×8mm,the diameter is 21 mm,or the height is 20 mm.The FLAC3 D simulation is used to compare and analyze the optimized solution.There is not much difference between the deformation values of the gateway roof and the two sides of rib,which indicates that the optimized scheme can meet the stability of the gateway and effectively control the surrounding rock deformation.At the same time,field engineering practice application results show that: the reduction of support strength saves support materials and reduces support costs.The cost can be saved to a maximum of 164 yuan/m,the saved support cost reached 2,143,500 yuan.Research results will promote efficient development of mining area.