Effect of Moisture Changes on Uplift Resistance of Buried Pipelines

Abstract

Buried pipelines form an integral part of urban and industrial infrastructure that ensures the safe transport of various fluids such as water, gas, oil, etc. The interaction of buried pipelines with surrounding soils significantly influences their mechanical behaviour and long-term stability. At shallow depths, this interaction is highly sensitive to climatic conditions, as the strength and deformation behaviour of the soil changes rapidly with moisture variations. Such moisture variations can lead to measurable changes in the strength and deformation behaviour of the soil. These variations in soil strength and deformation behaviour can further affect the pipeline support system, causing uplift, settlement, or lateral movements, leading to pipeline failure. It is, therefore, crucial to investigate such a phenomenon to avoid safety hazards, costly maintenance interventions, and disruptions in essential utility services. Based on the above viewpoints, the effect of such moisture variations in coarse and fine-grained soils on the uplift resistance of buried pipelines has been investigated in the present study. A thorough numerical investigation has been carried out using a commercially available software, Rocscience, to investigate the effect of varying moisture content on the strength and deformation behaviour of the surrounding soil and its interaction with the buried Pipeline at different depths. A unified effective stress approach was used to model the unsaturated behaviour of the soils, whereas the pipe was modelled as an elastic material. The findings highlight that moisture variations can significantly affect the uplift soil resistance in coarse and fine-grained soils, which can induce stress variations in the buried pipelines.