Study On Structural Safety Evaluation Of PCCP Under Working And Environmental Loads

Pre-stressed concrete cylinder pipe(PCCP)has been used widely in China for its good performance,large capacity,and cost-effective price.However,some PCCPs fail after a certain time of service because of deterioration such as crack and wire break,and lead to catastrophic consequences considering the pipe size and high internal pressure.Based on finite-element method and structural monitoring,this dissertation focus on the structural performance of PCCP under working and environmental loads.The mechanical performance and the mechanism of damage and failure were studied,and the structural conditions were evaluated.The research contents include the following aspects:(1)Mechanical performance analysis of PCCP under construction and working loads: The performances of integral PCCP and PCCP with broken wires were analyzed respectively based on ABAQUS,and some design parameters of mortar coating were discussed.The research shows that the structural capacity of integral PCCP is high while the capacity of PCCP with broken wires is much lower,and the most important factor influencing PCCP’s structural capacity is the number of broken wires.Meanwhile,there are some drawbacks in strength and crack-control strain limits of mortar coating in the design code of PCCP.(2)Mechanical performance analysis of PCCP under defective bedding conditions: The relative rotation features of PCCP,the distribution and development of strain in concrete core,the failure pattern of spigot and bell ends of the pipe and etc.were analyzed when non-uniform foundation settlement happens to PCCP pipeline,and the structural condition of PCCP was evaluated.The research shows that significant non-uniform foundation settlement can lead to the damage of spigot and bell ends,resulting in the acceleration of PCCP’s structural deterioration.(3)Structural performance monitoring of PCCP using distributed optical fiber sensors: Based on distributed optical fiber sensors,the structural monitoring of some PCCPs in a longdistance water supply project was conducted.The structural performance of PCCP was evaluated through distributed strain data collected,and the performance of distributed optical fiber sensors was also analyzed.The research shows that the distributed optical fiber sensors are able to describe the strains in PCCP accurately,and the comparison of monitoring results and numerical simulations indicate the PCCPs and the sensors are both in good condition.