Numerical investigations into the failure mode of buried prestressed concrete cylinder pipes under differential settlement

Abstract

In this paper, a prestressed concrete cylinder pipe (PCCP) pipeline under differential settlement is numerically investigated considering interface interactions and combined loads. An equivalent simplified model is first built to find the effective optimal model length under settlement. Based on a detailed model of the optimal length, the structural response and failure modes of the buried PCCP pipeline are discussed. Due to the rigidity of the PCCP, the joints are more sensitive to uneven foundation settlement than the barrels. When the differential settlement is greater than 35 cm, the relative joint angle easily exceeds the design regulation limit (0.5°). The damage and failure modes of the PCCP joint can be summarized as two types in which the spigot crown subjected to obvious bending or the joint top position is evidently compressed. With increasing differential settlement, the cracks in the pipe sections and joints are constantly widened and deepened, and they develop towards the pipe wall interior, creating the possibility for corrosive substances to invade the inner bearing components. The findings of this research highlight the influence of differential settlement to prevent further degradation and possible failure.