Seismic Response Analysis Of Utility Tunnel Under Rayleigh Waves

As an infrastructure of lifeline engineering,underground utility tunnel concentrates all kinds of municipal pipelines located above and below ground for unified maintenance and management.Underground utility tunnel can effectively solve the unreasonable utilization of underground space caused by the disorderly buried pipeline,and its good disaster prevention and reduction ability can effectively protect the municipal pipeline.At present,the seismic response of underground utility tunnel in China mainly focuses on wave excitation under P and SV wave,rarely under Rayleigh wave.Due to the shallow burial characteristics of the utility tunnel and the energy properties of Rayleigh waves(the energy of Rayleigh waves within the shallow surface layer accounts for about 67.3% of the total seismic input energy),Rayleigh waves become the key factors to be considered in seismic analysis of the structure of underground utility tunnel.This paper mainly studies the dynamic response of utility tunnel under the action of Rayleigh wave by means of numerical simulation.And the main work were listed as followings:1)The propagation characteristics of Rayleigh and its influence on structures and the seismic research of utility tunnel are investigated in this paper.The key problems in seismic research of underground structures are summarized and the research contents of this paper are put forward.2)Some key techniques to establish soil-tunnel interaction model with ABAQUS are briefly described.First,the introduction of Mohr-Coulomb model of soil and structure,the damage plasticity model of concrete and soil contact surface theory is illustrated.And then the viscoelastic artificial boundary and the infinite element artificial boundary and the equivalent load input method corresponding to these artificial boundary are derived,and the accuracy of the artificial boundary and its equivalent load of the infinite element is verified by an example.Finally,the selection of seismic waves is explained.3)The finite element model of soil-tunnel interaction is established,the influences of the cross-section size,structure constitution,cross-section shape,structural stiffness,seismic motion factors,friction coefficient and buried depth of the structure on the dynamic response of utility tunnel are investigated.The peak acceleration at each monitoring point,the relative horizontal displacement of the roof and floor,the shear angle and the maximum Mises stress in the structure were analyzed,and seismic suggestions were given.4)Based on the integral reaction displacement method and the approximate Rayleigh wave method,an integral reaction displacement method for underground utility tunnel under Rayleigh waves is proposed.In order to verify the effectiveness of the proposed method,the effects of different earthquake intensity and structural stiffness are investigated and its results were compared with those of the dynamic time history method.In both cases,the maximum error occurs at the top of the side wall of the utility tunnel,and the results of other parts are in good agreement with the dynamic time history method,which shows that the method proposed in this paper is feasible.