Research On Deformation And Failure Laws Of Surrounding Rock Of Gateways And Active Support Technology In Coalface

There are 5.6 trillion tons coal in China,accounting for 11% of the world’s total reserves,while oil only accounts for only 2.4% and natural gas is only 1.2%.Experts predicts that coal is still energy composition within 30 years ago.It will dominate the main position.At the time of coal mining,gateways are deformable and destroyed by the impact.In order to ensure safety,it is often necessary to carry out passive support such as U-shaped shed in the gateways,but it has high support costs and construction progress.Accompanied by a large amount of application of the cable(anchor cable)support technology in the tunnel,as well as low cost of the cable(anchor cable)support,using active support in the gateways,canceling passive support into a new development trend.However,due to the complexity of the entry,it is mainly designed to work mainly in the practice of engineering experience.labtest,site measurement,theoretical analysis and numerical simulation plan wering used to carry out the modifications and active support techniques of gateways,with a certain theoretical significance and engineering value.The main research conclusions are as follows:(1)Take the rock samples along the trough on the 21015 coalface of Chensilou coal for indoor testing.The results show that the porosity of the surrounding rock of the roadway is low,and the general strength is between 4.6 and 9.6 MPa.The least square method is used to obtain the Mohr-Coulomb strength criterion to describe the rock strength at the buried depth most accurately;(2)Using the elastic mechanics viewpoint and the generalized plane strain method,the mechanical model is established,and the influence law of the maximum horizontal stress and the roadway angle and the roadway inclination on the stress distribution around the roadway under the strike-slip in-situ stress state is obtained.The stress has a great influence on the roof.When the inclination angle is 45°～85°,the original axial stress becomes the hoop stress,and the three-zone load theory is used to find that the maximum stress of the working face is tangent to the mining fracture angle Value,mining depth,and working face length are in direct proportion;(3)Using the method of numerical simulation calculation and relying on the engineering background of Chensilou Coal Mine,it is concluded that the super-strong roadway roof stress varies from 1 to 16 MPa before and after the mining,and the lateral supporting pressure increases by 1.2 times;the advance supporting pressure of the working face increases from 21.8 MP.As large as 40.6MPa,the area of stress increase just before the work is within the range of 27～32m.Different mining stages have a greater impact on the vertical displacement of the roof.The roof of the roadway should be reinforced;(4)According to the size of the loose circle measured on site,the support plan of "bolt + anchor cable + metal mesh" is proposed,and the parameter range of the bolt(cable)is calculated,and the stress field and displacement field of the surrounding rock of the roadway under different support plans are simulated by FLAC 3D.Study the changes in the internal force of the bolt and determine the parameters of the final support plan;(5)The industrial test of active support along the channel on the 21015 working face of Chensilou coal was carried out,and the effect of active support was tested.The control effect was good and the project requirements were met.