Seismic Response Analysis Of Utility Tunnel Considering Joints Effects

As a special shallow buried underground structure for accommodating various types of pipelines in the city,utility tunnel has been widely used in the construction of various cities in recent years.Its advantage is that it effectively utilizes the underground space and avoids repeated road openings.At the same time,according to seismic damage data of utility tunnel,joints are the most severe part of earthquake damage.However,there are few studies on the seismic response of utility tunnel considering joints.Therefore,on the basis of the current research,using the finite element software ABAQUS to establish finite element model of utility tunnel considering two types of joints that are more commonly used in practical engineering,namely the bell and spigot joint and the bolt joint.And the influencing factors of the two models were analyzed.The main work are as follows:(1)Based on the finite element software ABAQUS,the soil-structure finite element model was established,and the basic theory and parameter selection of numerical modeling were determined,including model size,constitutive parameters(including soil constitutive,structural constitutive and bolt constitutive),element selection,setting of soil-structure interaction,artificial boundary conditions and seismic wave input,etc.(2)The seismic response analysis of utility tunnel considering the bell and spigot joint was carried out,and the seismic response of each factor to the utility tunnel was studied under two different directional earthquakes,different seismic wave and buried depth of the structure.The relative horizontal displacement,stress response of the bottom plate and the stress response of the joint section were analyzed.The results show that the seismic response of the horizontal seismic wave to the utility tunnel is greater than that of the vertical,while the two different directional seismic wave to the utility tunnel is much greater than single directional seismic wave,namely deformation is more likely to occur in two different directional seismic wave.And in the burying depth range of 2～3m,the displacement response of the utility tunnel,the stress response of structures and the stress response of joints will all increase with the increase of the buried depth.(3)The seismic response analysis of the utility tunnel with bolted joints was carried out,and the influences of the bolt prestress and position on seismic response of utitlity tunnel were investigated.At the same time,the mechanical properties of bolted joint utility tunnel were systematically analyzed from three aspects of stress development,deformation characteristics and displacement response.Finally,the difference in seismic response of the bell and spigot utility tunnel and bolt one was compared from the mechanical performance,deformation performance,and longitudinal bending rigidity efficiency.The results show that the bolts reduces the relative horizontal displacement of the structure to a certain extent,indicating that the bolts can strengthen the connection,but the more the number of bolts,the greater the stress concentration at the corresponding position of the utility tunnel.In terms of force difference,since the longitudinal bolts bear most of the tensile stress and the concrete bears the compressive stress,the performance of the bolts and concrete can be fully utilized.In terms of deformation difference,the top and bottom plates of the two types utility tunnel will have relative displacement,but the bolts limit the deformation to a certain extent,so that the overall seismic performance of the structure and the connectivity have been strengthened.In terms of efficiency difference of longitudinal bending stiffness,the longitudinal mid span deflection of bolted joint is less than that of the bell and spigot joint,and the longitudinal bending stiffness efficiency of bolted joint utility tunnel can be maintained at a high level before the bolt reaches the yield strength.