| The urban underground utility tunnel can ensure urban operation as an important infrastructure and "lifeline",so our country has made great efforts to develop the tunnel construction in recent years.However,because most cities are located in high seismicity region,it is important to conduct the seismic design and seismic response analysis for utility tunnel.At present,seismic response analysis of utility tunnel mainly mainly focuses on its simple structures along its direction and in local area(such as single compartment intersection and air vent)than the complex structures of compartment No.3 and No.4 intersection in tunnel.The intersection structure of urban utility tunnel is a pivot of connecting tunnel,which helps to maintain the safety of the whole structure.Moreover,because the intersection structure is one of the most complex parts of the wholoe tunnel system,it is worthwhile in engineering practice to analyze its seismic response and improve the seismic design of the structure.By using ABAQUS finite element software and dynamic time-history analysis method,focusing on the complex structure of intersection No.3 and No.4 of underground utility tunnel project in a city,this paper choose two different conditions of hard and soft geology and establish a three-dimensional numerical model of the intersection joint of utility tunnel.Based on the interaction between structure and soil,by using viscous boundary to input El-Centro seismic wave,the reference indexes of seismic performance of the composite pipe gallery,such as relative displacement,maximum displacement,acceleration of reference points and structural stress,are studied.Through orthogonal numerical simulation test,the influence of soil elastic modulus and cohesion on seismic performance of complex intersection structure of urban comprehensive pipeline gallery is analyzed and discussed.Summarizes the seismic response regularities of complex intersection structure.The results show that the relative displacement increases with the the structure depth under seismic effects.(1)In terms of structure,the connection of its baseplate and component is the part sufferred the greatest impact by seism,the surrounding wall is directly affected by the soil,so its stress and strain are more obvious than other parts.(2)Under the condition of soft soil,the structure easily be damaged by seism due to the increase of the stress,maximum displacement and relative displacement in each part of the structure,and the obvious concentration of baseplate stress and the larger roof stress.Under different geological conditions,there are the similar movement trend of seism in the tunnel structures,where the larger stress also appears at the same place,and the change of geological conditions will affect the seismic response of the structure except the similar dynamic response regularies.(3)The stress and strain values of the structure of Hatch 3-4 intersection under earthquake action decrease with the increase of elastic modulus of soil,and decrease with the increase of cohesion.The research results of this paper can provide reference for seismic design of urban utility tunnel intersection. |
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