Full-scale test study on the mechanical response of ultra-large section jacking prestressed concrete cylinder pipe (JPCCP) under axial jacking force

Jacking prestressed concrete cylinder pipe (JPCCP) represents an innovative composite pipe technology wellsuited for water supply and drainage projects. Currently, JPCCP designs frequently reference existing prestressed concrete cylinder pipe (PCCP) and pipe jacking standards, neglecting the impact of axial jacking force on the composite structure's performance and the highly nonlinear issues encountered during the jacking process, such as concrete cracking, dislocation, and prestress loss. To thoroughly investigate the structural performance of JPCCP, this study, conducted in conjunction with the ultra-large-section JPCCP project in China, carried out axial loading tests both within the launching shaft and before entering the soil. The mechanical response of the concrete structure during the jacking process was investigated, culminating in the formulation of an axial strain calculation model for JPCCP. The results indicate that, owing to the combined effects of non-full-section eccentric compression and jacking force transmission, the axial deformation of the exterior-reinforced concrete was generally greater than that of the intermediate concrete, and the transfer of jacking force within the exterior-reinforced concrete was more pronounced. Additionally, the concrete deformation at the spigot end was marginally smaller than at the bell end, exhibiting more uniform deformation; however, abrupt changes in the cross-section at the spigot end can induce localized tensile stress areas. The discrepancies between theoretical calculations and actual test results remain within 10%, and the impact of prestress loss on different layers of concrete was inconsistent. This investigation into the structural performance and calculation model of ultra-large section JPCCP furnishes valuable insights for the design and construction of JPCCP.