Study On Rationality Of Bolt Support Schemes Of Roadway In No.3 Coal Seam In Dongfeng Coal Mine

With the development and the application of the bolt support design,the bolting support has become the main support pattern in the roadway.The conditions of roadway are complicated and the theories of the bolting support are limited.These make the bolting support unreasonable in many coal mines.The roadway of No.3 coal seam in Dongfeng Coal Mine is taken as research object.Analyzed the condition,it show that the roadway is light section and integrated.And the thickness of sandstone stratum is 6.5m above the floor,it is hard and uneasy to be failure.Therefore,it is better for the roadway stability.The design theory of bolt support is analyzed and point out that the bolt mainly reinforce and suspend surrounding rock in broken rock mass,improve stress state of surrounding rock.lt shows that the length of cable becomes short gradually from min-span to two sides with same bearing capacity through analyzing the robustness of the cable.And the robustness becomes good gradually with same length in the same conditions.The mechanical parameters of coal rock mass are measured in the laboratory.Study the failure and deformation of roadway and the robustness of cable through similar material simulation on experiment,and show that the caving angles is 55°,and the caving height is almost 2m,and the cable in mid-span is steadier than in eccentric arrangement.Then based on project analogy method,the scheme of bolt-cable combined supporting with cable arranging eccentrically is designed.Compared with the original scheme,it mainly cuts a row of cable and shortens the length of cable from 8.4m to 6m.Analyze the the safety,the driving speed and the economic benefit of the new and original schemes by numerical analysis and engineering test.The result show that the new scheme can make roadway safe and steady with the driving speed increased by 12.5%and the cost decreased by 17.5%.