Three-dimensional finite element modeling of corrugated metal pipes

The mechanism of the soil-structure interaction in buried corrugated metal pipes (CMPs) depends primarily on the relative stiffness of the flexible buried pipe and the surrounding compacted backfill material. Several geometric, mechanical, and material characteristics control this complex composite interaction, including the shape and dimensions of the pipe, its burial depth, the effect of the backfill compaction, and existing in-situ conditions. Numerical techniques such as the finite element method (FEM) have proved useful in capturing the soil-structure interaction. This paper presents three rigorous three-dimensional finite element models of circular, horizontal ellipse, and arch pipes with spans of 600 mm, 1800 mm, and 6000 mm, respectively. The models developed account for the effect of compaction on the soil behaviour. These models were validated by using three full-scale tests of underground CMPs. The FEM results are compared with recorded measurements of deformation and internal forces in each pipe structure. The effectiveness and suitability of three commonly used constitutive soil models, the Mohr-Coulomb (MC) model, the hardening soil (HS) model, and the hardening soil with small strains (HSs) model, are also examined. The HSs model exhibited the best fit in simulating the interaction of the backfill soil and buried pipes with different types of loading.