Cui Jiaming, Xing Guohua, Miao Pengyong, Hu Wenbo, Chang Zhaoqun
Prestressed Concrete Cylinder Pipe (PCCP) is commonly utilized in major water conveyance systems. During its service life, PCCP pipes are prone to deformation of the pipe body and failure of the joint due to soil pressure, internal water pressure, and vehicle loads, leading to leakage and endangering operational safety. A finite element model of single and double-row PCCP pipes considering pipe-soil interaction was established to analyze the stress characteristics of PCCP under different pipe diameters, burial depths, internal pressures, and vehicle positions, and evaluate its service safety risks. The results indicate that: The circumferential Mises peak stress of each layer of material and joint in a single-row PCCP pipe is negatively correlated with pipe diameter and internal pressure, and positively correlated with burial depth and load offset. As the diameter and internal pressure increase, the bearing capacity of the pipeline is enhanced. When the load is applied between two pipes, the maximum Mises stress on the pipe body and joint is reduced by about 3% and 20%, respectively, compared to a single pipe, and degree of stress reduction on the joint increases from 20% to 30% as the pipe diameter increases from 2 800 mm to 4 000 mm. When the load is applied to one side of the double pipe, the maximum Mises stress of the pipe body and joint is reduced by about 2% and 18%, respectively, compared to the single pipe, and the degree of stress reduction on the joint increases from 18% to 25% with the increase of pipe diameter. Indicating that double-row laying can effectively counteract external loads and enhance the bearing capacity of pipes. The safety risk assessment of single-row and double-row PCCP pipes shows that when the pipe diameter is small and the burial depth is 3 200 mm, there is a risk of micro crack formation in the local concrete of the pipe. The pipe exceeds the limit state when the internal pressure is more than 0.8 MPa. The double-row laying of small pipes is greatly affected by vehicle loads and is prone to exceeding the limit state of the pipe. As the pipe diameter increases, the double-row laying gradually becomes safer.
