| Prestressed concrete cylinder pipes(PCCP)have been widely used in water conveyance projects all over the world for its unique structural characteristics and excellent performance since its appearance.In recent years,many pipes burst accidents have occurred in PCCP used in domestic and foreign projects,which have attracted the attention of researchers at home and abroad.For the development of PCCP in China,the application of PCCP started late,and the theoretical research and numerical simulation of its structural characteristics are not deep enough,especially the mechanism of PCCP failure and even tube burst during operation needs further study.In this paper,on the basis of summarizing the research status and trends at home and abroad,combined with PCCP in practical engineering,using ABAQUS finite element software,the broken wires model of the pipeline is established,and the mechanical properties of each part of the pipeline are studied,which has important theoretical and practical significance.The purpose of this study is to explore how the location of broken wires(spigot end,bell end,middle of pipe)and the number of broken wires(setting different broken wires rate)affect the structural strength of PCCP.In order to provide reasonable suggestions and reference for the design,manufacture,construction and operation of PCCP.The main contents are as follows:(1)This paper summarizes the advantages,disadvantages and application scope of commonly used pipe materials in pressure water conveyance project.Combined with the actual project,the prestressed steel cylinder concrete pipes is used as the water conveyance pipeline of a pumping station project in Xiaochang by adopting the method of pipeline economic comparison.(2)The basic theory of PCCP structure calculation is studied and summarized.Combined with PCCP selected in engineering,the safety and reliability of pipeline is verified by theoretical method.(3)Because of the existing finite element model,most of them didn’t consider the influence of spigot end and bell end on the bearing capacity of pipes,and the model is too simplified.The research establishes a finite element model considering the characteristics of spigot end and bell end.The model adopts the composite element model.Based on the consideration of the contact between layers,the influence of different internal water pressures on the mechanical properties of the pipe components under normal operating conditions was studied.The results show that under normal operation condition,the pipe structure is under the safe scope of stress,and the core concrete and mortar coating will not appear cracks,and at the same time,it further verifies the safety and reliability of the pipes in the project.(4)The broken wires model were established to study the influence of broken wires rate(5%,10%,15%,20%,25%,30%)at different positions(spigot end,bell end,middle part of pipe)of PCCP under internal water pressure of 0.8 MPa,1.12 MPa 1.3 MPa,1.4 MPa,1.51 MPa.It is found that the bearing capacity of the pipe is greatly reduced when the broken wires occurs,and the influence of the broken wires on the core concrete and the mortar coating is more obvious.The concrete and mortar coating in the broken wires area appear cracks first,and the internal water pressure in this area is mainly borne by the steel cylinder and the prestressed steel wires.After comparing and analyzing the influence of the change of broken wires position on the bearing capacity of pipes structure,it is found that the spigot end of the pipe is damaged first,then the middle of the pipe,and finally the bell end of the pipe. |
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