Study On Cooperative Control Mechanism Of Pressure Relief With Roof Cutting And Energy Absorption Support With Constant Resistance In Extra-thick Hard Roof Roadway

The roadways of most mines in China are vulnerable to the mining influence of adjacent working faces.Especially when the mining height is large and the roof is hard,it is easy to cause mine earthquake events and other dynamic phenomena.The mining pressure appears violently,resulting in life and property losses.Therefore,taking Caojiatan 122108 working face as the engineering background,this paper carries out the research on pressure relief and energy absorption control for the extra-thick coal seam and extra-thick hard roof roadway.Through the research means of combining numerical simulation and model test,the surrounding rock control mechanism of the extra-thick coal seam and extra-thick hard roof roadway was clarified.And then,the test data and guidance were provided for the field engineering application.The main conclusions are as follows:(1)The cooperative control idea and method of ultra-deep hole roof cutting and pressure relief and high pre-stress constant resistance support are put forward,so as to control the roadway with extra-thick coal seam and extra-thick hard roof.The numerical comparison test of pressure relief and energy absorption control of extra-thick hard roof roadway is carried out.The control effect of roadway surrounding rock is compared.The variation law of surrounding rock stress,deformation and roadway roof support force are studied.The advantage of ultradeep hole roof cutting and pressure relief and high pre-stress constant resistance support cooperative control method for this kind of roadway surrounding rock control is clarified.(2)The numerical comparative experimental research on different pressure relief parameters of extra-thick hard roof roadway is carried out.The control effect of deep hole directional roof cutting and reinforced blasting parameters on roadway surrounding rock is studied.And the pressure relief parameters are reasonably selected.For the roadway with extrathick coal seam and extra-thick hard roof roof,the roof cutting height of 20m～30m and the roof cutting angle of about 30° are the parameter selection range with obvious control effect of roof cutting and pressure relief of roadway surrounding rock.The enhanced blasting angle of 5～10° away from the roof cutting direction is the parameter selection range with obvious control effect on the auxiliary roof cutting of the roadway.(3)The simulation device of directional roof cutting and constant resistance support are developed.The comparative model test of pressure relief and energy absorption control of extra-thick hard roof roof roadway is carried out.It is concluded that the stress and deformation of roadway surrounding rock after ultra-deep hole roof cutting and constant resistance energy absorption support are lower than those of non-roof cutting roadway.The maximum stress and deformation of roof cutting roadway combined with reinforced blasting and constant resistance support can be reduced by 40.87%and 52.26%respectively.The mechanism of the cooperative control method for this kind of roadway surrounding rock control is clarified.The correctness of numerical test and the effectiveness of the collaborative control method were verified,which guides the design and engineering application of roadway pressure relief parameters.(4)Combined with the results of numerical simulation and physical model test,the field test of ultra-deep hole roof cutting pressure relief and constant resistance support is carried out.The parameters of roof cutting pressure relief,enhanced blasting and constant resistance energy absorption support are designed for the on-site roadway.The monitoring results of roadway support stress and surrounding rock deformation show that the field application effect is good.The difference rate between field test data and model test data is 14.78%,which verifies the rationality and effectiveness of model test data.