Seismic Response Analysis Of Cross Joint In The Utility Tunnel

With the intensification of urbanization in China,the d emand for the types and capacity of municipal pipelines is expanding constantly.The traditional construction way of urban pipeline is no longer suitable for the needs of urban planning at this stage.The underground utility tunnel has become the best solu tion to the growing demand for municipal pipelines.At present,the state is actively promoting the construction of utility tunnel.Many cities have constructed the utility tunnels,some of which have been put into use.However,the seismic researches of t he utility tunnel in our country is still in the preliminary stage,and most of the researches only emphasize on the seismic response along with the length of the tunnel,but without considering the seismic response of the cross joints.In fact,due to the coupling effect of the earthquake in the variable cross-section of the cross joints,the stress of the joints is more complex than other parts.Based on the existing experimental and theoretical research results,this paper analyzes the seismic response in the cross joints of the utility tunnel,summarizes the reaction law of utility tunnel joints and explores the reason of the reaction law with finite element simulation method.Combing with the destruction of cross joints,this paper gives some advice on the aseismic design.The main contents of this paper include:Firstly,the paper illuminates the key questions of the utility tunnel in numerical simulation,the material constitutive relation,the theory of soil-junction contact,the artificial boundary of dynamic infinite element and th e input method of ground motion included.Secondly,combined with the existing research results,the parameters of the material parameters,unit type,artificial boundary conditions and the input method of ground motions involved in the numerical simulation are analyzed.Based on this,the numerical model of underground utility tunnel was built.Finally,through the numerical simulation,the difference of the response characteristics of the cross joint in the underground utility tunnel between the uni-directional and bio-directional earthquake action is analyzed;the influence of multi-parameter on the response of the underground utility tunnel under the action of uni-directional and bio-directional earthquake action is systematically studied;the complex destruction modes of the underground utility tunnel intersecting joints under uni-directional and bio-directional earthquake action are revealed;the most dangerous parts and links under the interaction of the cross joints are identified.The results of the study show that,in the case of unidirectional seismic action,it is necessary to consider the joint destruction and the linkage destruction of the nearby tunnel;in the case of bio-directional seismic action,except considering the underground utility tunnel cross joints possible destruction forms under uni-directional earthquake action,the buckling failure in the direction of non-main earthquake action also needs to be considered.The final conclusion of the paper provides a good reference for the seismic design of the underground utility tunnel cross joints.