Physical Testing and Finite Element Analysis of a Corrugated High-Density Polyethylene Stormwater Arch Under Deep Burial

Abstract

The performance of a corrugated, high-density polyethylene stormwater retention arch subjected to deep burial conditions was investigated. Current design methods are based on evaluation of performance under both shallow and deep burial conditions. Although field testing and two-dimensional finite element analyses have been carried out during the development of these arched chambers, there has been an absence of high quality laboratory testing and three-dimensional finite element investigation of the failure mechanism and the ultimate limit state under deep burial conditions. This thesis first presents results from a full-scale experiment of two buried, corrugated, high-density polyethylene arches with a 350 mm rise, 690 mm span, and 150 mm spacing surrounded by uncompacted gravel backfill under simulated deep burial conditions. Both performance during backfill and under simulated deep burial conditions up to an applied pressure of 280 kPa were evaluated. Research quantified the structural performance by the evaluation of limit states, examination of global stability, detection of onset and progression of local buckling, and inferred soil behaviour of surrounding backfill. Performance was dominated by large vertical deflections and through-thickness thrusts, with local buckling beginning under an applied pressure of 220 kPa. Second, a three-dimensional finite element analysis was conducted and validated against the physical measurements. Material nonlinearity of the structure material was represented by an updated viscoplastic formulation to account for lower strain rates, while the surrounding backfill material was represented by a linear-elastic, plastic formulation with a Mohr-Coulomb failure criteria and non-associated plastic flow. The model took geometrical nonlinearity into account as the corrugation geometry responded to the applied pressure. Time-dependent behaviour was noted under constant load holds, particularly during the increments once the ultimate limit state had been reached. The explicit three-dimensional finite element model of the buried arches was able to successfully simulate behaviour measured in the physical experiment. A parametric study was then performed to capitalize on the calibrated analysis and extend this work by performing a series of parametric studies which considered factors including soil and structure material parameters, interface constraints, development of local buckling, backfilling effects, and spacing of parallel arches.