| The large-scale construction of Underground utility tunnel has been constructed on a large scale in China.With the advantages of short construction period and low site conditions,prefabricated utility tunnel has been widely used.As an important urban lifeline engineering,the underground utility tunnel will suffer serious economic losses and secondary disasters under earthquake.The utility tunnel belongs to a shallow underground structure,which is similar to the tunnel and has its own characteristics.At present,there are few and no corresponding codes for seismic research of utility tunnel,and the results of seismic research of underground structures cannot be imitated completely.The utility tunnel has a long span and spatial variability of ground motions.Based on a comprehensive utility tunnel in Fuzhou,the rigid-connected utility tunnel-soil model and the prefabricated utility tunnel-joint-soil model are established respectively to analyze the ground motions under uniform and non-uniform excitations.The main work of the thesis is:(1)Select the ground motion intensity index suitable for shallow-buried underground utility tunnel.According to the one-dimensional algorithm and the nodal motion equation,the seismic wave is transformed into the equivalent load applied on the boundary nodes and internal nodes to realize the wave input.The corresponding program is compiled by using the MATLAB language,and the feasibility of the program is verified.Taking the utility tunnel as the research object,the two-dimensional seismic response analysis model of utility tunnel-foundation system is established by software ABAQUS.Seismic wave of 80 third class sites is selected from PEER database for dynamic analysis.Four kinds of intensity indexes,acceleration type,velocity type,displacement type and mixed type,are compared.The structural response and seismic intensity of single-storey,double-storey and two-storey four-storey utility tunnel are calculated.The indexes are compared and analyzed,and the suitable indexes for shallow underground utility tunnel are selected.The correlation rules between structural response and various strength indices are obtained.Suggestions on selection of seismic strength indices for large-section utility tunnel are put forward.(2)Three-dimensional seismic response analysis considering the dynamic interaction between utility tunnel and soil.Based on the derived one-dimensional finite element method of free wave field and extended to three-dimensional According to traveling wave law,and a MATLAB program for calculating the equivalent load of non-uniform seismic is developed.A three-dimensional finite element numerical model of the interaction between utility tunnel and soil is established to analyze the response of site and utility tunnel under the uniform excitation of transverse and longitudinal seismic waves.The seismic response analysis under oblique incidence is studied by changing the incident angle,and the influence of different thickness of soft soil layer on seismic response is studied by changing its soil conditions.This paper summarized the weak position of utility tunnel section under earthquakes,and puts forward reinforcement suggestions.(3)The response of prefabricated utility tunnel joints considering traveling wave effect is analyzed.Finally,through the compression simulation of prefabricated composite utility tunnel joints with a water swelling rubber,the compression curve is obtained.the joint is simplified,and the three-dimensional seismic response analysis model of prefabricated composite utility tunnel-joint-soil is established.The response of joints at different connection stiffness,different apparent wave velocity and different prefabricated standard section lengths is analyzed,and the prefabricated composite utility tunnel is analyzed.The response law of traveling wave effect to joints at different axial locations is obtained,which provides a reference for the longitudinal seismic research of prefabricated composite utility tunnel. |
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