Response Mechanism Of Underground Utility Tunnel In Qinghu South Section Under Earthquake

The rapid development of underground utility tunnels in recent years has brought great economic benefits to society.The 1995 Hanshin earthquake caused extremely serious damage to many underground structures and affected the normal operation of the city.therefore,this paper quantitatively analyses the effects of unidirectional and bidirectional coupled ground vibrations on the corridor structure under the same burial depth by means of theoretical analysis and numerical simulation,and the relationship between bidirectional coupled ground vibrations and burial depth The relationship between bi-directional coupled ground vibration and burial depth is also investigated.The following work is accomplished in this paper.(1)Based on the theory of semi-infinite space of soil,part of the soil and the underground utility tunnels are regarded as finite domain through reasonable division,and the action of semi-infinite soil is equated by simulating the viscous-spring artificial boundary attached to the soil,and the overall dynamic analysis model is realised through ABAQUS in conjunction with MATLAB.The Mohr-coulomb model was used for the soil and the concrete damage plasticity model was used for the structure,comparing the classical theory with the modified method in ABAQUS.(2)By simulating the seismic effects of unidirectional and bidirectional coupled seismic waves on the gallery,it was found that the damage of the gallery was mainly caused by uncoordinated deformation,in which the load-bearing response of the intermediate wall was extremely critical.Under the action of horizontal ground shaking,the intermediate wall undergoes large inter-storey displacement,and the horizontal reaction force leads to through cracks at both ends of the wall,reducing the vertical bearing capacity of the part;under the action of vertical ground shaking,the structural axial pressure changes drastically,and the vertical load borne by the top of the intermediate wall accounts for half of the total load,leading to damage damage by overfilling the bottom of the intermediate wall with pressure damage;comprehensive two-way action,the intermediate wall loses its bearing capacity The vertical load borne by the structure is transferred to the top and side walls,which in turn bends the top plate too much and eventually causes damage to the structure.Throughout the process,the intermediate walls assume an extremely important seismic role and are the key components of the corridor’s seismic resistance,while the two-way coupling ground vibration input method is the most rigorous and reasonable.(3)To explore the relationship between the burial depth of the same structure and the seismic action,by comparing the maximum principal stress field of the soil,it was found that the soil-arch effect appeared as the burial depth increased,and comparing the information on surface settlement,vertical relative displacement of the structure,axial compression ratio,shear ratio and inter-storey displacement angle under different burial depths,it was determined that the burial depth had an amplifying effect on the seismic action,but at the same time,the maximum value and residual value of the vertical load borne by the structure were compared.The existence of the soil arch effect was verified.