Study On Wall Rock Stability Of The Three-centered Arch Tunnel Near The Fault

With the development and progress of the national economy,the above-ground traffic engineering has gradually failed to meet the growing needs of people,and the underground tunnel engineering came into being.The stability of tunnel wall rock deserves attention.Based on the disturbance and damage caused by the tunnel excavation,the factors affecting the stability of the wall rock of the three-centered arch tunnel near the fault were discussed,and based on a project simulates it by FLAC 3D finite differential software by controlling variable method.(1)The influence of horizontal position on the stability of tunnel is analyzed,and the stress and displacement changes of vault,hance,arch foot and arch bottom as well as the size of plastic zone of wall rock are recorded,and based on this project the main conclusions are as follows: when the tunnel and fault distance is 0m,the tunnel plastic zone is the largest,the distance between the tunnel and the fault is 0m,and the stress is greatest when the distance between the tunnel and the fault is 8m,the tunnel plastic zone is larger when the inverse fault is excavated,The greater the floating of stress and displacement,the more dangerous the construction,stress floats at 0～39.09% and displacement floats 4%～169.84% when digging at different positions.(2)The influence of fault dip angle on tunnel stability is analyzed,and the stress and displacement changes of tunnel vault,hance,arch foot and arch bottom as well as the size of wall rock plastic zone are recorded,and based on this project the main conclusions are as follows: the maximum zone of tunnel plastic zone is at 30 degrees at the angle of faults,the stress and displacement of the tunnel wall rock are the largest at an inclination of 45 degrees,Therefore,when the dip angle of the fault is between 30 °and 45 °,the structural stress near the fault is obvious and the stability of the tunnel is poor.(3)The influence of internal friction angle on tunnel stability is analyzed,and the stress and displacement changes of vault,hance,arch foot and arch bottom as well as the size of plastic zone of wall rock are recorded,and based on this project the main conclusions are as follows: the maximum zone of tunnel plastic zone is 20 degrees at the inner friction angle,the stress of tunnel wall rock is directly proportional to the internal friction angle,and the displacement is inversely proportional to the internal friction angle.It shows that when other mechanical parameters are the same,the strength of wall rock with larger internal friction angle is higher,which is conducive to the stability of wall rock and engineering safety.(4)This paper analyze and summarize the influence of factors such as the horizontal position,fault dip angle,and the friction angle within the rock formation on the stability of the wall rock of the tunnel.Finally,combined with the engineering example of the Yonglian Tunnel of the Gillian Expressway,the influence of lining structure on tunnel stability is analyzed and verified,which provides theoretical support and reference for similar cases in the future.