Mechanical Analysis Of Buried Box Culvert Subjected To The Landslide

Sewerage pipes are important infrastructures of urban flood-proof and sewage transmission. It is necessary to analyze the mechanical behavior of drainage pipe in various working situations for the safe of the municipal sewerage pipeline system. On the background of Chongqing downtown sewerage system's A pipeline project, the response of the buried box culvert to landslide were analyzed. The main work and conclusions were present as follows:Firstly, the current method of landslide thrust calculating was introduced. The landslide-thrust of typical part of A line by means of load transfer factor method was calculated. Mechanical model of buried pipe was created when landslide occurred, and then inner force and deformation equations, including shear effect, was obtained. The analyzed results showed that shear deformation had a tremendous influence to longitudinal displacement of spanning pipe, with a little effect of pipeline inner force. The soil of the foundation played an apparently bearing action to pipe. The least favorable situation was that the pipe was completely suspended.Secondly, prototyping with A pipeline typical buried box culvert, model beam was designed and statically tested in structural laboratory of Chongqing University. The crack distribution of test beam was uniform, and there was no critical declining crack in beam body. We could conclude that the failure mode of test beam was shear failure. About the mechanical process of the test beam, four stages could be characterized as web-shearing declining crack stage, flexural crack stage, flexure-shearing declining crack stage and diagonal rod squashing stage. The flexural deformation was main before the test beam cracked, while shear effect was less. The shear stiffness of the component sharply decreased after declining crack developed a wide certain. After the component reached its ultimate bearing capacity, the deflection was increasing a lot as a result of much reinforcement in bottom plate. On the whole, the test beam did not suddenly corrupt.The experimental results betrayed that the stirrups devoted much to shear capacity of the box girder. The longitudinal steel strain in bottom plate presented a linearly increasing process, but abruptly mutated when flexural crack occurred. Only in a small part was there shear lag effect because the longitudinal steel strain was influenced by many other factors. From the distribution principles of longitudinal bars, it was demonstrated that the test beam could not accord with plane cross-section assumption whether cracking or not.Finally, the test beam was modeled by damage-plastic model in the nonlinear finite-element software ABAQUS. The simulated results agreed well with the experimental data, especially for the failure mode of the box beam. However, all of the deflection in every sub-step was less than that in testing process owing to the larger stiffness of finite-element model. The finite-element results demonstrated that there was shear lag effect in longitudinal rebar in the bottom plate. The plane cross-section assumption was also satisfacted for the longitudinal steel in the web plate of the box beam.