Structural response of non-perforated and perforated corrugated high-density polyethylene pipes under variable loading

Abstract

The structural response of small diameter (<300 mm) corrugated high-density polyethylene (HDPE) drainage pipes installed on agricultural lands, has not been thoroughly examined. Additionally, characteristics of imposed wheel loads from agricultural field machinery are not adequately represented in conventional structural design practises for buried pipes. This study investigates the response of single-wall corrugated HDPE pipes (100 mm diameter) under loading from 12 agricultural soil textures, two water table positions, and three agri-machinery wheel loads using a finite-element-based numerical model. Effects from two friction conditions (smooth and bonded) at the soil-pipe interface were assessed. Simulations were also done to determine the impact of variable perforation characteristics (shape, size, and configuration) on the stress distribution and deformation of the corrugated pipes. The results show that bonded friction conditions generally induce larger stresses in the pipe wall than smooth friction conditions, but the differences are not statistically significant across all soil and load types. The critical load case occurs for a loaded grain wagon on silt loam soils. The results also indicate that perforations in the pipe wall induce high stress concentrations at the edges of rectangular slots and circular holes, increasing the risk for failure by ductile yielding. Specifically, corrugated HDPE pipes perforated with 5.6 mm diameter holes produce stresses that exceed the yield strength at buried depths shallower than 0.9 m. In conclusion, perforation characteristics should be considered when assessing the structural adequacy of corrugated HDPE pipes for land drainage.