| In this thesis,combined with the on-site geological conditions of Huafeng Coal Mine,comprehensive use of theoretical analysis,numerical simulation and on-site monitoring methods are used to study the stress evolution law and plastic zone change law of the-1180 West Rock Roadway during advancement process of 2613 working face of Huafeng Coal Mine,deformation characteristics of roadway surrounding rock and variation law of supporting load of supporting body.The failure mechanism of surrounding rock disturbed by deep rock tunnel excavation is proposed,and based on the failure mechanism of surrounding rock disturbed by deep rock tunnel excavation,a support optimization plan is proposed.The feasibility of the optimized scheme is verified by numerical simulation.The main tasks completed in this paper are as follows:(1)In-depth investigation and analysis of the occurrence characteristics of coal and rock layers in Huafeng Coal Mine-1180 West Rock Roadway,support schemes,roadway deformation and failure conditions,and coal and rock layers occurrence characteristics in the2613 working face have been determined,and the roadway surrounding rock deformation has been determined.The main causes of damage are: The buried depth of the roadway is large,and it is greatly affected by the horizontal tectonic stress;the roadway is close to the working face,and it is greatly affected by the excavation disturbance.The surrounding rock stress peak of the surrounding rock of the roadway continuously shifts outwards under the influence of the excavation disturbance,causing the fragmentation area to expand continuously.The increase of the crushing pressure of the surrounding rock leads to the deformation and failure of the surrounding rock and supporting structure of the roadway;insufficient bearing capacity of existing support body in roadway,etc.(2)Four measuring points were selected in the-1180 West Rock Roadway for on-site monitoring.When the mining line is at different distances from the roadway monitoring point during the advancement of the working face,the borehole stress of the roadway surrounding rock,the bearing capacity of the support body and the evolution law of the surrounding rock deformation of the roadway were analyzed.It is found that the original stress field of the roadway changes under the influence of excavation disturbance.The borehole stress in the shallow surrounding rock of the roadway gradually decreased,and the borehole stress in the deep surrounding rock first increased and then decreased.It shows that under the influence of excavation disturbance,the surrounding rock in the shallow part of the roadway is gradually broken,the peak stress of the surrounding rock gradually shifts outward,the load on the support body is gradually increased,and the deformation of the roadway is also gradually increasing.A formula fitting is carried out on the data of on-site monitoring roadway deformation,and the law of roadway deformation is analyzed through the fitting formula when the roadway is continuously approaching and moving away from the mining line.(3)Numerical simulation software was used to simulate the whole process of roadway destruction during the advancing process of working face,and the evolution laws of vertical stress,horizontal stress,principal stress difference,plastic zone and roadway displacement and deformation were analyzed when the mining line of working face is at different distances from the monitoring section of the roadway.It is found that under the influence of mining disturbance,the original stress field of roadway enters the stress redistribution,and the roadway stress release area expands and develops in a direction parallel to the mining face.The shallow surrounding rock cannot withstand the gradually increasing stress and is released through deformation.With high stress,the fracture zone of surrounding rock of roadway continues to expand,and the plastic zone of surrounding rock is also expanding and developing toward the working face.The peak stress of surrounding rock gradually shifts to the depth.The expansion of the fragmentation zone leads to an increase in the swelling pressure of surrounding rock,resulting in increase in the load acting on the supporting body.When the load acting on the support body exceeds the ultimate bearing capacity of the support body,the roadway support structure gradually deforms and breaks,and the roadway deforms and loses stability.A numerical simulation of excavation disturbance is established,the correctness of the model is verified by monitoring data,the field monitoring data is supplemented by numerical simulation,and the excavation disturbance mechanism and failure of surrounding rock in deep rock tunnels is revealed.(4)According to the distance between the roadway and the mining line of the working face,the influence of excavation disturbance on different roadways can be divided into three stages: weak disturbance stage,disturbance enhancement stage and disturbance weakening stage.When the mining line is far away,the roadway is in a weak disturbance stage.At this time,the stress of the surrounding rock of the roadway is in a balanced state,the supporting structure is stable,and the roadway is not deformed or damaged;As the mining line approaches,the roadway enters a stage of enhanced disturbance.At this time,the roadway is gradually affected by the excavation disturbance,the surrounding rock stress is redistributed,the stress peak shifts to the interior of the surrounding rock,and the surrounding rock fragmentation area gradually increases.The deformation gradually intensifies,and the bearing load of the support body gradually increases.After the bearing capacity of the support body is exceeded,the support fails and the roadway is deformed and destroyed;When the mining line gradually moves away from the roadway,the roadway enters the weakening stage of disturbance.At this time,the excavation disturbance weakens,the roadway is affected by the stress release in the goaf,the surrounding rock stress redistribution gradually ends,and the supporting body load is gradually stabilized.(5)According to the failure mechanism of surrounding rock disturbed by the excavation of deep rock tunnels,a composite support technology of anchor mesh shotcrete + steel pipe concrete support + grouting reinforcement is proposed.Under the condition of improving the supporting force of the active and passive supporting structure,the shallow surrounding rock is grouted and reinforced,the stability of the shallow surrounding rock is improved,and flexible fillers are filled between the surrounding rock and the concrete-filled steel tube support.Numerical simulation analysis verifies the feasibility of the new support scheme.The new support scheme can better control the roadway deformation under the influence of excavation disturbance and ensure the roadway stability.Based on theoretical analysis,a full-section wall-breaking and pressure-relief support technology is initially proposed.The use of full-section wall-breaking and pressure-relief support technology can release large deformations of surrounding rock and reduce the load acting on the supporting structure,which is beneficial to maintain long-term stability of the roadway and lower support costs. |
PDF Full Text Request