Failure Test And Mechanical Properties Study Of Prestressed Steel Cylinder Concrete Pipe Joints

Prestressed concrete cylinder pipe(PCCP)makes full use of the compressive and corrosion resistance of concrete and mortar as well as the tensile and sealing properties of steel,which can bear high internal water pressure and external load,and is widely used in various water delivery projects.the bell-spigot joints belongs to the semi-rigid joint,the uneven foundation,the live load,the groundwater,and other factors will cause the uneven settlement of the pipeline,resulting in the relative angle of the joint,the deformation of the joint and the failure of the rubber ring,and even cause water leakage accidents.The study on the failure modes of PCCP joint is significance to the safe operation and maintenance of the pipeline.In this study,a full-scale test about PCCP joint is carried out,and a three dimensional numerical model of buried PCCP,considering the simulation of rubber gasket in bell-and-spigot joint is established.The main contents are as follows:(1)A prestressed concrete cylinder pipe with an inside diameter of 1400 mm is used to the full-scale test about relative angle,and the mechanical responses of mortar coating,concrete core and prestressed wires under different relative angles are obtained.The failure mode of the joint is that the rubber ring sliding out from the steel ring,and the relative angle is 1.92° when it fails.(2)In this paper,ABAQUS software is used to detail the modeling of each component of PCCP,Then the process of generating corner between pipes was simulated and the finite element model was estimated using the test results.Based on the evaluate model,the mechanical behavior of other pipe diameters PCCP socket relative rotation angle was simulated,and the displacement of the pipe end when the PCCP joints of 1400 mm,2000 mm,2600 mm and 4000 mm pipe diameters failed were obtained as follows: 190 mm,180 mm,170 mm,150 mm,The relative rotation angles between pipes at failure were 1.83°,1.72°,1.62°,and 1.43°,respectively.In the process of increasing the displacement of the pipe end,the circular and the axial strain of each material at the socket is relatively large in the crown and the bottom area of the pipe;the stress state of the prestressing steel and the mortar protection layer is the same.(3)Based on MpCCI coupling platform,the finite element model of pipe soilfluid-solid coupling was established by using ABAQUS and FLUENT software.the joint failure mechanism is studied under different settlement conditions during the operation of PCCP.The results shown that visible crack will occur in the concrete when the vertical relative displacement are 83 mm,75.49 mm,and 83 mm.And the concrete damage occurs first at the root of crown.Along the hoop direction,the damage extends from the crown to both sides,and along the axial direction,the damage extends from the root of spigot to both sides...