Study On Instability Mechanism And Pressure Support Technology Of High Stress Soft Roadway

Since the new century has entered,the coal mining has been developing to the deep.With the increase of the mining depth the ground stress is also rising.The traditional hard rock will change to the soft rock under the high stress.Because the plastic deformation of the soft rock is serious and the duration is longer,the problem of the high stress soft rock support will be the need for the deep development of the coal mining.In this thesis,the high stress soft rock roadway is taken as the research object.Firstly,the failure mechanism of high stress soft rock roadway is analyzed by using theoretical analysis method,and it is concluded that the deformation and failure of high stress soft rock roadway can not be avoided.The controllable deformation of roadway surrounding rock is beneficial to the overall stability.Secondly,through analyzing the anchoring mechanism of pressure support,it is concluded that the transfer yielding support can absorb the huge energy of surrounding rock deformation,combine with the surrounding rock to bear the external load,and on this basis,the dimension of the yielding tube is optimized by ABAQUS simulation software.Finally,the wall thickness 3mm,the Q235B steel type and the middle drum diameter 42mm are determined as the optimum parameters.The yielding bolt structure is improved,the anchor head and brace are strengthened,and the anchoring force is increased.At last,through the comparative analysis of four different schemes by FLAC3D simulation software,it is found that the deformation of the bolt after compression is slightly increased,but it is still within the controllable range,and the axial force of the bolt in the system is smaller,and the number of the anchor in the yielding state is less.The support system is more stable.Based on the engineering background of the track roadway in the east wing of Xiaoyun Coal Mine,the traditional supporting scheme is improved.Under the guidance of theory and numerical simulation conclusion,the support density and support mode of roadway are optimized.Finally,the combined support scheme of,bolt shotcreting(yielding bolt)+anchor cable+lag grouting" is put forward to solve the problem of roadway support.Through the monitoring data and field deformation,it can be known that the improved support scheme can effectively control the deformation of roadway,and the stress state of bolt and cable is stable,and the supporting system is in good working condition.