A Novel Experimental Technique to Investigate Soil–Pipeline Interaction under Axial Loading in Saturated and Unsaturated Sands

Abstract

Abstract Comprehensive experimental and numerical models are required for reliable investigation of unsaturated soil-structure interaction problems. In this study, a reliable testing technique and a numerical modeling methodology were developed to study the performance of a buried pipeline system in sand subjected to relative soil movement in a direction parallel to its axis under both saturated and unsaturated conditions. A novel testing system was developed using a specially designed test box of 1.5-m length, 1.2-m width, and 1.1-m height. The system utilizes the hanging column technique to achieve different soil matric suction profiles. The experimental results on the tested sand suggest that the measured axial force exerted on a pipe in unsaturated sand is significantly higher compared with the saturated condition. The measured behavior of the prototype pipe was numerically modeled using the commercial software SIGMA/W extending the principles of saturated and unsaturated soil mechanics. The predicted axial force, following the suggested finite element analysis (FEA) methodology, is in good agreement with the measured axial force on the tested prototype pipe. Both the experimental technique and numerical method proposed in this article are useful for the practicing engineers in the rational design of pipelines in sandy soils, taking account of the influence of saturated and unsaturated conditions in sandy soils.