Mechanical Characteristics Analysis Of The Connection Section Of Prefabricated Pipe Gallery Under Asymmetrical Load

With the continuous improvement of urban infrastructure in China,the construction of underground comprehensive pipe gallery has become the main trend and necessary development direction of municipal public pipeline laying.The joint form of the connecting section of the comprehensive pipe gallery is the key node and important guarantee for the effective function of the pipe gallery in the service cycle.It has important theoretical guidance and practical significance to explore the mechanical characteristics and applicability of different forms of pipe gallery joints under asymmetric traffic load in the actual engineering environment.In order to study the mechanical response law of the pipe gallery connection under asymmetric load,field prototype test is carried out in this paper,and the three-dimensional numerical model of the pipe gallery and soil is established,and the mechanical characteristics of the pipe gallery connection under asymmetric load are further discussed.The main work and conclusions are as follows:(1)Based on the field prototype test,the distribution of earth pressure and the mechanical response characteristics of each measuring point under the unsymmetrical vehicle load are studied.The field test shows that under the action of unsymmetrical vehicle,the pressure stress of the left wall is the largest when it is viewed clockwise along the inner wall of the pipe gallery along the direction of vehicle travel.From the inner wall to the left side wall and the haunch corner of the roof,the compressive stress is greatly reduced.To the middle part of the roof span,the stress of the pipe gallery changes from compressive stress to tensile stress.(2)Based on the field prototype test,combined with the finite element software ABAQUS,the tunnel soil model is established,and the half wave sine curve is established to simulate the vehicle load model under asymmetric load.Through the comparative analysis of the numerical simulation results and test results,the reasonable accuracy of the numerical model is verified.(3)Based on the verified numerical model,considering the influence of different asymmetrical load positions(0m,1m,2m along the side line of the pipe gallery),different asymmetrical load amplitudes(0.7MPa,1.4Mpa,2.1 MPa),different interface forms(socket type and flat type)of the pipe gallery connection section,the mechanical characteristics of the comprehensive pipe gallery connection section under the asymmetrical load are studied.The results show that:the maximum principal stress at the roof of the pipe gallery is most affected by asymmetric load.The maximum tensile stress(quarter span position of the roof)of the pipe gallery is reduced by about 30%compared with the original loading position when the asymmetric loading position is shifted outward by 1 m.The vertical displacement of the socket end of the connecting section of the pipe gallery appears obvious asymmetry.When the asymmetric load loading position is offset by 1m outward,the vertical displacement of each position of the pipe gallery is reduced by about 15%relative to the original loading position.From the perspective of the internal force of the pipe gallery,the effect of asymmetric loading has a greater influence on the connection way of the pipe socket and less influence on the flat mouth way.When the connection way of the pipe gallery is in the form of a flat port,the force of the pipe gallery is smaller than that of the socket,and the structure is safer.The vertical displacement of each part of the flat end of the pipe gallery is smaller than that of the socket end of the pipe gallery.