| Utility tunnel is a modern and intensive urban infrastructure,there are two or more urban municipal pipelines in the tunnel,it is called "common ditch" in Japan.Because the utility tunnel is a buried structure with a tunnel form,its overall stiffness is larger than the other aboveground buildings,it can make full use of the urban underground space.The utility tunnel can preferably withstand all kinds of natural disasters such as earthquakes,typhoons and freezing,it is considered to be one of the most effective ways to solve the current urban development chaos.It is becoming more and more important in the modernization of our city.The structure of utility tunnel will inevitably be affected by different earthquake motion in the working,but the research of utility tunnel under earthquake by domestic and foreign scholars are still immature,vulnerability analysis of utility tunnel under earthquake is less and less,so the vulnerability analysis of utility tunnel under earthquake is studied from the model in the paper.The main work of this paper is as follows:(1)The development background and characteristics of utility tunnel is explained,the development history and current situation of utility tunnel at home and abroad is studied,and the advantages and shortcomings between construction of utility tunnel are summarized.The damage and current situation of utility tunnel under earthquake are studied,and several research methods of underground structure are summarized under earthquake.(2)The basic theory of finite element,the process of finite element analysis and the soil constitution are introduced.The concrete constitution between seismic code and provided in ANSYS are compared.The advantages and shortcomings of viscous boundary,transmitting boundary and viscous spring boundary are summarized separately.The superiority of seismic wave spread in the soil with viscous spring boundary is verified.The contact of soil and underground structure is introduced,and the selection principle and type of contact element in ANSYS are also introduced in detail.(3)The basic assumptions of the modeling process is produced,The parameters of soil and concrete constitutive are determined,The size and mesh of the finite element model are determined,using the way of point-point contact to achieve contact between soil to tunnel structure.Set two direction spring element in order to format viscous spring boundary in the range of venue.According to the seismic design parameters of Shanghai PuDong area,the standard design response spectrum curve is generated,on the basis of design response spectrum,thirteen earthquake waves are selected from the database of PEER.Adjust the peak of each seismic wave from 0.1g to 1.0g,and then input them to the finite element model,the vulnerability of utility tunnel is analysis according to the response of displacement.(4)Introducing the method and step of incremental dynamic vulnerability.Did the modal analysis of utility tunnel finite element,according to the natural frequency from modal analysis,the damping ratio is get according to Rayleigh damping formula.The seismic response of utility tunnel is analyzed under the earthquake motion of Chi-Chi.The damage condition and performance level are defined according to the stress-strain curve of concrete.According to the results of nonlinear analysis,the vulnerability analysis is conducted with the method of probabilistic seismic demand analysis,and get the vulnerability curve based on two performance parameters,then summarized the damage probability of utility tunnel structure according to the shape of vulnerability curves.(5)The conclusion of this paper is summarized,and explained some inadequacies in the research process.Through the prospect of the future,the following research directions and ideas of this subject are determined. |
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