Research On Mechanics Model And Control Of Floor Heaves In Gob-side Entry

The gob-side entry retaining has advantages of relieving roadway excavation tension,achieving the ventilate type of "Y",improving the recovery rate,so the technology develop rapidly in recent years,but serious floor heave phenomenon is one of the bottlenecks restricts the development of technology.In this paper multiple methodlogies including theoretical analysis,numerical simulation,simulation experiment and field test were used in this work.The key questions needing to be answered included gob-side entry floor of deformation rule and characteristic,Establish the mechanical model of the floor heave of gob-side entry retaining;the distribution law of floor stress and the range of floor failure,the control technology of floor heave,the main research results are as follows:(1)The law of deformation and characteristic in gob-side entry: the deformation mainly occurred range from in front of working face 40 m to behind face 80 m.The advance influence range of the second working face floor of the gob-side entry is 0~80m.In front of the first working face,the working surface of floor deformation and failure degree were higher than the solid coal body side,the stage of gob-side the solid coal body side floor deformation degree were greater than driftside body side.(2)Using complex function theory to analysis the distribution law and influencing factors of floor: The floor corner stress concentration degree is larger;With the increase of the roadway aspect ratio of the corner and the floor stress decreases;With the increase of coefficient of horizontal pressure,the corner stress increases,the floor stress decreases;With the increases of buried depth,and bottom floor stress were increased;(3)Through the analysis of the faliure if roof in gob-side entry,bearing capacity of asymmetric structure of the both sides of the roadway,then established the mechanical model of gob-side entry,based on the theory of semi infinite plane,deduced the floor stress formula,using D-P criterion to calculate the floor damage range.(4)According to the dynamic change process of the stress contour and failure curvce of the floor in gob-side entry retaining,to revealing the mechanism of floor heave: With the increase of the stress and damage range of floor plate,a part of the floor heave is produced by the deformation of the newly added damaged rock mass,and the other part of the floor heave is procuded by the failure of the damaged rock mass under the greater stress.With the decrease of the stress and damage range of the floor plate,only the deformation of the rock mass under the action of small stress,so the floor heave redeces.Because of the asymmetry of the floor stress and the damage range,cause the characteristic of floor heave is asymmetry.(5)Strengthening the roof and both sides of roadway can reduce the stress and damage range of the floor,so it can effectively control the floor heave;The bottom anchor can not only improve the stress strength of the weak rock,and can improve the residual strength of rock,Through the reasonable installation angle,it can exert the maximum reinforcement effect,and achieve to control the floor heave effectively.A case study has indicated that the proposed control strategies could effectively reduce the amount of the floor heave in 3107 auxiliary air intake in XinYuan coal mine...