Soil-pipeline interaction in unsaturated soils
type: CreativeWork
description: Pipelines that are used for the transport of energy and services are very important lifelines to modem society. Though pipelines are generally buried in unsaturated soils, the design guidelines are based on the assumption that the soil is either dry or fully saturated. For certain geotechnical problems, this assumption may not be acceptable because the water meniscus formed between soil particles creates an additional normal force between them by suction, which in turn forms temporary bonds. A recent series of large-scale physical model experiments at the Pipeline Engineering Research Laboratory (PERL) of Tokyo Gas, Japan show a higher peak load under unsaturated conditions compared to dry conditions. In contrast, recent experiments performed at Cornell University (CU) show that the soil-load due to lateral pipeline movement in dry and unsaturated sands are virtually the same. Thus, the effect of partial saturation on soil loading to pipeline may be different depending on soil type, moisture content and density. The current study investigates this problem through triaxial testing and constitutive modelling of the unsaturated soils used for the experiments and finite element simulations of the experiments. The mechanical behaviour of the sands used in the physical model experiments has been investigated by conducting a series of laboratory experiments. When compacted to the same energy level, Tokyo Gas sand exhibits larger strength in unsaturated conditions than in dry conditions at low confining stress levels mainly due to the suction-induced apparent cohesion generated by the fine particles present in the sand. In contrast, for coarser Cornell sand, the suction effect is found to be small even at low confining stress level, and hence the strength in unsaturated conditions is similar to that in dry ( or fully saturated) conditions. To capture the observed behaviour of dry as well as unsaturated soils, advanced constitutive soil models were developed. For dry (or ful…
abstract: Pipelines that are used for the transport of energy and services are very important lifelines to modem society. Though pipelines are generally buried in unsaturated soils, the design guidelines are based on the assumption that the soil is either dry or fully saturated. For certain geotechnical problems, this assumption may not be acceptable because the water meniscus formed between soil particles creates an additional normal force between them by suction, which in turn forms temporary bonds. A recent series of large-scale physical model experiments at the Pipeline Engineering Research Laboratory (PERL) of Tokyo Gas, Japan show a higher peak load under unsaturated conditions compared to dry conditions. In contrast, recent experiments performed at Cornell University (CU) show that the soil-load due to lateral pipeline movement in dry and unsaturated sands are virtually the same. Thus, the effect of partial saturation on soil loading to pipeline may be different depending on soil type, moisture content and density. The current study investigates this problem through triaxial testing and constitutive modelling of the unsaturated soils used for the experiments and finite element simulations of the experiments. The mechanical behaviour of the sands used in the physical model experiments has been investigated by conducting a series of laboratory experiments. When compacted to the same energy level, Tokyo Gas sand exhibits larger strength in unsaturated conditions than in dry conditions at low confining stress levels mainly due to the suction-induced apparent cohesion generated by the fine particles present in the sand. In contrast, for coarser Cornell sand, the suction effect is found to be small even at low confining stress level, and hence the strength in unsaturated conditions is similar to that in dry ( or fully saturated) conditions. To capture the observed behaviour of dry as well as unsaturated soils, advanced constitutive soil models were developed. For dry (or ful…
author: Robert, Dilan Jeyachandran
language: eng
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/ad4d546a-5b74-4a8c-8276-21b16f61c0ab/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2010-10-12
date modified: 2026-07-22T22:24:11Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.11686