Numerical Simulation Of Prestressed Concrete Cylinder Pipe (PCCP) In Operation

Prestressed Concrete Cylinder Pipe(PCCP)for its inside and outside can withstand the high pressure,corrosion resistance,strong ability in water permeability and convenient installation,good practicability and economy,and is widely used in municipal,electricity,and water conservancy projects,especially the national major projects-the south-north water diversion project,like me.Therefore,pipeline running safety and stability is particularly important in the process of PCCP simulation model is established reasonably according to the engineering practice,analysis of piping stress distribution,working condition of cracks and damage,so as to provide reference for practical engineering,is very meaningful and very necessary.This paper summarizes the development course and its design principle and standard of the development in China,introduces the process and key points of the process.According to the actual research present situation and the middle route of south-to-north water transfer project is chosen embedded prestressed concrete cylinder pipe(PCCP-E),numerical simulation model is established by using ANSYS,so as to reasonably in the model considering the relationship between the layers of connections,cooling method is used to simulate prestressing,analysis wrapped silk complete,gravity,hydrostatic pressure,different internal water pressure and heavy vehicle under different working conditions,such as pipe inner and outer layer tube core concrete,steel cylinder and stress change rule of the prestressed steel wire.The main conclusions are as follows:(1)The wire wrapping is completed,the inner layer and the outer layer pipe core concrete and steel tube will appear axial stress,radial stress and circumferential stress,the radial stress is small,has no effect on the crack can be ignored,mainly for the axial stress and circumferential stress,but compared to concrete and steel tube tensile and compressive strength are very small,does not cause crack.(2)The normal operation of the pipeline(water pressure from the hydrostatic pressure to the design pressure 0.84MPa),the normal stress on the parts of the pipe,no cracks.(3)In the limit of internal pressure(water pressure is 1.2MPa),the main stress of the pipeline is hoop stress.The maximum circumferential tensile stress of 2.65 MPa inner core concrete,exceed the tensile strength standard value of C50 concrete(2.64MPa),the continuing role when the inner core concrete to crack along the ring,the flow along the cracks,causing damage;steel tube and prestressing steel wire strength to meet the capacity requirements,does not appear to yield.At the same time,in the long-term use,the creep of concrete,the erosion of chloride ions,the relaxation of prestressed steel wire and ground moving load will cause the pipeline failure,the superposition of multiple factors will accelerate the pipeline damage.(4)Heavy vehicle loading,when the tube top central region stress exceeds 2MPa,the inner core concrete,maximum axial tensile stress appears at the bottom of central2.4MPa,very close to the standard value of concrete tensile strength of C50(2.64MPa),it is prone to axial crack;the maximal circumferential tensile stress appears in the at the end of the central tube,for more than 3.06 MPa,the tensile strength standard value of C50 concrete(2.64MPa),the inner tube to the core concrete cracks along the ring,when the internal water pressure,will accelerate the crack extension caused by pipeline failure,danger to traffic.Therefore,in actual engineering,it is necessary to reduce the loss if we can strengthen the operation monitoring of the pipeline,find out the damage and take measures in time.