Responses of buried steel pipes under footing loadings – a numerical parametric study

Abstract

Buried pipes are among the most important urban facilities due to their use in multiple key applications such as drainage, sewerage, oil lines, electrical conduits, and culverts. The performance of such infrastructure under different loading conditions relies highly on their design, yet adequate design cannot be achieved unless their actual behaviours are well understood. This paper thus uses numerical analyses to investigate the response in terms of vertical stresses of buried steel pipes under monotonic static footing loads. Based on a reduced-scale physical test constructed in a test box under plane-strain conditions, a finite element model was built and verified using Plaxis3D software, and a parametric study to investigate the effects of footing width and loading condition, and pipe location or embedment ratio was then conducted. The results of the numerical analyses showed that the Hardening Soil (HS) model depicted the response of the backfill material adequately. The numerical analysis results also showed that increasing embedment depth decreased the pressure on the pipe, while increasing the footing width increased the pressure on the pipe when the embankment height was twice the pipe diameter. A critical footing width of 1B was identified that was responsible for the highest pressure on the pipe when the embankment height was equal to the pipe diameter (H/D = 1). When H/D = 1, the localised footing loading condition is thus critical due to the higher vertical stresses on the pipe than seen under uniform loading.