| Prestressed Concrete Cylinder Pipe(PCCP)is a common water transfer pipe,which is widely used in many water transfer projects due to its composite pipe structure.For pressurized water pipeline,the pressure it can withstand is an important indicator of the performance of PCCP structure,PCCP protective layer is easy to crack under transient pressure,thus affecting the bearing capacity of the pipe,and in serious cases,even lead to bursting and other engineering accidents,in addition,PCCP pipe jacking construction,there are often deflection angle,resulting in complex conduit force.In this paper,for reinforced concrete protective layer PCCP pipe,finite element analysis software ABAQUS is used to study its bearing capacity and analyze the effect of deflection angle on the bearing capacity of this PCCP pipe during jacking,the main research contents and conclusions are as follows:(1)The modeling method of PCCP pipe and the selection of material instantiation model in the model as well as the simulation method of steel wire pre-stress are discussed,and the reasonable value of concrete damage plastic instantiation model is briefly analyzed.The numerical simulation model of PCCP is created by combining the specific parameters of PCCP pipe in the actual project,and the force characteristics of PCCP are analyzed under the action of wire wrapping and cracking resistance external pressure experiments,and the numerical simulation results are compared and analyzed with the theoretical results of the code and the test results to verify the feasibility of the modeling method.(2)Simulation studies of PCCP with three different protective layers(mortar,concrete,and reinforced concrete)under the action of internal pressure were carried out to compare the magnitude of cracking internal pressure of PCCP with three different protective layers,and the similarities and differences in the degree of structural cracking damage under the action of the same internal pressure load were compared by the concrete CDP damage plasticity model,and it was found that the reinforced concrete protective layer had the highest bearing capacity,2.0 MPa internal pressure load mortar protective layer and concrete protective layer damage factor of 0.83,0.84,respectively,reinforced concrete protective layer is 0.75,when the protective layer damage degree is the same,reinforced concrete protective layer PCCP bearing capacity than concrete protective layer PCCP 31.4% greater than the mortar protective layer PCCP 26.5% greater than.(3)In the process of linear jacking,three different types of protective layer(mortar,concrete,reinforced concrete)PCCP pipe stressing situation is considered,and the effect of different locations of the jacking force(jacking force uniformly applied to the core part of the pipe prestressing,protective layer,full section)on the pipe stressing is simulated.It is found that when the top force is uniformly applied on the full section,the stress distribution of the pipe is basically the same as when the top force is fully applied on the pipe core,however,when the top force is uniformly applied on the protective layer,the structural stress distribution changes significantly,and at this time,the protective layer compressive stress is the largest.(4)The turning angles of pipe joints are 0.3°,0.5° and 1.0° respectively to analyze the stresses on the pipe during the deflection jacking process and get the influence law.It was found that the stress level of socket steel ring increased with the increase of deflection angle of pipe jacking;under the same deflection angle,the difference of jacking force area had almost no effect on the stress size and distribution of socket steel ring;the axial compressive stress showed a decreasing trend with the increase of protective layer thickness at the deflection pressure of PCCP pipe with three protective layers.The axial compressive stress of reinforced concrete protective layer is 17.7% smaller than that of mortar protective layer and 7.1%smaller than that of concrete protective layer. |
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