Research On The Control Mechanism Of The Surrounding Rock Of The Thin-thick Combined Shell In Deep Soft Rock Roadway

The Yangdong Mine-850 horizontal return air tunnel has a buried depth of 1000 m.It belongs to a deep soft rock tunnel.The surrounding rock creep of the tunnel is prominent,and the tunnel has large deformations.It is unable to stabilize itself for a long time and needs to be repaired many times.In order to solve the above problems,this thesis has studied the instability law of the surrounding rock of deep soft rock roadway disturbed by repairing through laboratory experiment,theoretical derivation,numerical simulation experiment and similar material simulation experiment,and developed the roadway thin and thick composite shell support structure,Reveals the control mechanism of the thickthin composite shell support structure of the roadway on the surrounding rock,analyzes the applicability of the thin and thick composite shell structure of the roadway under different lateral pressure coefficients and the influence of the corrugated steel material strength on the control effect of the composite shell structure.(1)The lateral pressure coefficient of the-850 horizontal area of Yangdong Mine is measured to be between 1.23 and 1.42.The maximum horizontal principal stress is obliquely intersected with the return air tunnel at a large angle,and there is a vertical crack at 5.8m in the surrounding rock.,Carrying out rock mineral composition analysis and disintegration resistance test,the analysis shows that after the rock encounters water,the water and the material in the rock undergo physical and chemical reactions,the structure skeleton is destroyed,the rock properties are deteriorated,and the roadway appears large deformation and failure.(2)According to the disturbance phenomenon of the surrounding rock caused by the repeated maintenance of the roadway in the actual project,the laboratory rock mechanics experiment was carried out to study the failure law of the rock under different stress paths.The equivalent section model after multiple repairs after the surrounding rock of the roadway is damaged.(3)A support structure of thick-thin composite shells for roadways is proposed,in which corrugated steel and gap filling bodies are used as thin shells,and surrounding rock and anchor casting bodies are used as thick shells.The two shells are mechanically connected through bolts and cables to control The surrounding rock of the roadway is deformed greatly.The role of each component of the roadway's thin-thick composite shell supporting structure is analyzed,and the formula for roadway displacement after stress redistribution,the formula for the radius of the plastic zone,the formula for support resistance,and the formula for total support strength are deduced.(4)Based on the experimental results of physical mechanics and actual geological data,a numerical simulation model was constructed.By changing the lateral pressure coefficient of the model,analysis of the plastic zone change law,stress evolution law,bolt and anchor cable force law and roadway deformation law of the surrounding rock of the roadway,the results show that the general roadway thin-thick composite shell structure is suitable for the side pressure coefficient of 0.5?2.0 Under working conditions,when the lateral pressure coefficient is greater than 2.0,the surrounding rock will be locally damaged.(5)Choose three corrugated steel materials with different strengths to build three similar material models of the thin and thick combined shell of the roadway,determine the experimental similarity ratio and the proportion number according to geological data and laboratory experiments,and obtain the increased corrugated steel material through controlled loading It is concluded that the thickness and the improvement of the stiffness of corrugated steel materials can improve the support effect of the thin and thick composite shell of the roadway.