Numerical soil model for analysing sewer pipe-soil interactions

Determining the load bearing capacity of a deteriorated sewer is one of the important aspects to assess the overall condition of the sewer pipe system. Current indicators to achieve an impression of the residual bearing strength of the pipe are the age of the pipe and footage obtained by camera inspection (CCTV). However, these indicators have proven not to be very accurate, which makes the need for a reliable method to estimate the load bearing capacity of sewers high. The finite element method (FEM) is a suitable analysis tool for gaining a detailed understanding of the load bearing capacity of in-situ sewer pipes. The load bearing capacity does not only depend on the geometrical and material parameters of the pipe itself, but also on the deformation and failure behaviour of the soil structure supporting the pipe. The present contribution discusses the numerical implementation of an advanced soil model that can be used in a finite element analysis of a sewer pipe-soil system, which is a first step in the development of a computational model that is able to accurately predict the overall failure response of sewer pipe systems under arbitrary in-situ conditions.