Study On Control Principle Of Reconstructed Bearing Layer Of Surrounding Rock In Deep Mine Roadway

With the increase of mining depth,the deformation and the control difficulty of surrounding rock are increasing.how to control the deformation of mine is one of the key to realize the high yield and high efficiency.For the large deformation problems in deep mines,the concept of reconstructed bearing layer was proposed.The deformation of surrounding rock was controlled by improving the mechanical properties of the roadway surrounding rock in a certain range to creat a stable macro environment and using basic support to improve micro environment.Using the theoretical analysis,numerical simulation and similar simulation,the reasonable parameters,control mechanism,implementation method of the reconstructed bearing layer were researched.Relationship between various factors of bearing layer and strength of composite bearing body was analyzed by uniaxial compressive test.When the bearing layer thickness accounted for more than 60%~70%,the strength of the composite bearing body tended to the strength of the bearing layer.The strength rule of composite bearing body was explained by Mohr strength theory and the view point of energy conversion.Surface displacement and plastic zone of reconstructed bearing layer of roadway were analyzed with uniaxial compressive strength tests of composite bearing body and elastic-plastic mechanics.Reasonable length of reconstructed bearing layer should be equal to the plastic zone radius.Thickness of reconstructed bearing layer should be as much as possible.The sensitivity of reconstructed bearing layer parameters on roadway stability was analyzed by using orthogonal numerical test.When bearing layer was in sides,with the increase of the thickness,the vertical stress of shallow sides was increased but the one of deep sides was reduced,so that the vertical stress became homogeneous.With the increase of the length,the peak stress continued to decrease,and peak position was shifed to the deep part.Reasonable thickness is 3/4 of the roadway height,and the reasonable length should be equal to the plastic zone radius.Implementation method of installation of steel tube and grouting in sides was presented,and formed concrete filled steel tube had the effect of the beam and bolt.By similar simulation experiments on reconstructed bearing layer in sides,some results were made.Relative to the bared roadway,the extent of damage of roof and two sideswere effectively reduced,but the magnitude of floor-heave was significantly increased.After using reconstructed bearing layer and basic support,the damage extent of surrounding rock was fully decreased.By improving the bearing capacity of two sides and making the vertical stress uniform,the displacement and the distribution of plastic zone of the surrounding rock can be reduced with constructed bearing layer.It is a new attempt method to control the surrounding rock in deep mine roadway.