Effect of water content and soil texture on consolidation in unsaturated soils

Wei-Cheng Lo, Jhe Wei Lee

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Soil consolidation, involving time-dependent coupling between deformation of a porous medium and interstitial fluid flows within it, is of relevance to many subsurface engineering problems. A comprehensive model of poroelasticity for consolidation in unsaturated soils has been recently developed by Lo et al. (2014), but it still remains elusive how variations in soil texture and water content affect consolidation behavior, and the underlying parameters deriving this behavior.In the current study, a boundary-value problem is first setup corresponding to two symmetric semi-permeable drainage conditions, and then solved analytically for describing the excess pore air and water pressures along with the total settlement in response to time-invariant external loading using the Laplace transform. These solutions are numerically calculated for unsaturated soils with eleven texture classes as a function of three initial water saturations as representative examples. Our results reveal that the excess pore water pressure and time-dependent total settlement are indeed significantly sensitive to both soil texture and initial water saturation. We demonstrate that the coefficient of consolidation for water and its loading efficiency are two important physical parameters controlling consolidation behavior. With respect to the same soil texture, the coefficient of consolidation for water increases with an increase in initial water saturation, taking a value approximately four to five orders of magnitude greater in saturated soils than that in unsaturated ones. For a given initial water saturation, the rate of dissipation of excess pore water pressure is smallest in clay, followed by silty clay, silty clay loam, sandy clay, clay loam, silt loam, loam, sandy clay loam, sandy loam, loamy sand, and sand. A comparative study shows that in the early stage of consolidation, unsaturated soils bear smaller excess pore water pressure, but its dissipation is completed faster in saturated soils. The loading efficiency for water exhibits a concave upward relationship with initial water saturation in silty clay and clay, whereas a positively-correlated relationship between the efficiency and initial water saturation is observed in other soil textures. Unlike saturated soils, a considerable amount of total settlement is shown to occur immediately after application of external loading.

Original languageEnglish
Pages (from-to)51-69
Number of pages19
JournalAdvances in Water Resources
Volume82
DOIs
Publication statusPublished - 2015 Aug 1

Fingerprint

soil texture
consolidation
water content
saturation
soil
water
porewater
silty clay
loam
dissipation
effect
poroelasticity
sandy clay loam
silty clay loam
clay
sandy clay
Laplace transform
loamy sand
clay loam
sandy loam

All Science Journal Classification (ASJC) codes

  • Water Science and Technology

Cite this

@article{182d641bac0e4f0da60d57dd8935390e,
title = "Effect of water content and soil texture on consolidation in unsaturated soils",
abstract = "Soil consolidation, involving time-dependent coupling between deformation of a porous medium and interstitial fluid flows within it, is of relevance to many subsurface engineering problems. A comprehensive model of poroelasticity for consolidation in unsaturated soils has been recently developed by Lo et al. (2014), but it still remains elusive how variations in soil texture and water content affect consolidation behavior, and the underlying parameters deriving this behavior.In the current study, a boundary-value problem is first setup corresponding to two symmetric semi-permeable drainage conditions, and then solved analytically for describing the excess pore air and water pressures along with the total settlement in response to time-invariant external loading using the Laplace transform. These solutions are numerically calculated for unsaturated soils with eleven texture classes as a function of three initial water saturations as representative examples. Our results reveal that the excess pore water pressure and time-dependent total settlement are indeed significantly sensitive to both soil texture and initial water saturation. We demonstrate that the coefficient of consolidation for water and its loading efficiency are two important physical parameters controlling consolidation behavior. With respect to the same soil texture, the coefficient of consolidation for water increases with an increase in initial water saturation, taking a value approximately four to five orders of magnitude greater in saturated soils than that in unsaturated ones. For a given initial water saturation, the rate of dissipation of excess pore water pressure is smallest in clay, followed by silty clay, silty clay loam, sandy clay, clay loam, silt loam, loam, sandy clay loam, sandy loam, loamy sand, and sand. A comparative study shows that in the early stage of consolidation, unsaturated soils bear smaller excess pore water pressure, but its dissipation is completed faster in saturated soils. The loading efficiency for water exhibits a concave upward relationship with initial water saturation in silty clay and clay, whereas a positively-correlated relationship between the efficiency and initial water saturation is observed in other soil textures. Unlike saturated soils, a considerable amount of total settlement is shown to occur immediately after application of external loading.",
author = "Wei-Cheng Lo and Lee, {Jhe Wei}",
year = "2015",
month = "8",
day = "1",
doi = "10.1016/j.advwatres.2015.04.004",
language = "English",
volume = "82",
pages = "51--69",
journal = "Advances in Water Resources",
issn = "0309-1708",
publisher = "Elsevier Limited",

}

Effect of water content and soil texture on consolidation in unsaturated soils. / Lo, Wei-Cheng; Lee, Jhe Wei.

In: Advances in Water Resources, Vol. 82, 01.08.2015, p. 51-69.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Effect of water content and soil texture on consolidation in unsaturated soils

AU - Lo, Wei-Cheng

AU - Lee, Jhe Wei

PY - 2015/8/1

Y1 - 2015/8/1

N2 - Soil consolidation, involving time-dependent coupling between deformation of a porous medium and interstitial fluid flows within it, is of relevance to many subsurface engineering problems. A comprehensive model of poroelasticity for consolidation in unsaturated soils has been recently developed by Lo et al. (2014), but it still remains elusive how variations in soil texture and water content affect consolidation behavior, and the underlying parameters deriving this behavior.In the current study, a boundary-value problem is first setup corresponding to two symmetric semi-permeable drainage conditions, and then solved analytically for describing the excess pore air and water pressures along with the total settlement in response to time-invariant external loading using the Laplace transform. These solutions are numerically calculated for unsaturated soils with eleven texture classes as a function of three initial water saturations as representative examples. Our results reveal that the excess pore water pressure and time-dependent total settlement are indeed significantly sensitive to both soil texture and initial water saturation. We demonstrate that the coefficient of consolidation for water and its loading efficiency are two important physical parameters controlling consolidation behavior. With respect to the same soil texture, the coefficient of consolidation for water increases with an increase in initial water saturation, taking a value approximately four to five orders of magnitude greater in saturated soils than that in unsaturated ones. For a given initial water saturation, the rate of dissipation of excess pore water pressure is smallest in clay, followed by silty clay, silty clay loam, sandy clay, clay loam, silt loam, loam, sandy clay loam, sandy loam, loamy sand, and sand. A comparative study shows that in the early stage of consolidation, unsaturated soils bear smaller excess pore water pressure, but its dissipation is completed faster in saturated soils. The loading efficiency for water exhibits a concave upward relationship with initial water saturation in silty clay and clay, whereas a positively-correlated relationship between the efficiency and initial water saturation is observed in other soil textures. Unlike saturated soils, a considerable amount of total settlement is shown to occur immediately after application of external loading.

AB - Soil consolidation, involving time-dependent coupling between deformation of a porous medium and interstitial fluid flows within it, is of relevance to many subsurface engineering problems. A comprehensive model of poroelasticity for consolidation in unsaturated soils has been recently developed by Lo et al. (2014), but it still remains elusive how variations in soil texture and water content affect consolidation behavior, and the underlying parameters deriving this behavior.In the current study, a boundary-value problem is first setup corresponding to two symmetric semi-permeable drainage conditions, and then solved analytically for describing the excess pore air and water pressures along with the total settlement in response to time-invariant external loading using the Laplace transform. These solutions are numerically calculated for unsaturated soils with eleven texture classes as a function of three initial water saturations as representative examples. Our results reveal that the excess pore water pressure and time-dependent total settlement are indeed significantly sensitive to both soil texture and initial water saturation. We demonstrate that the coefficient of consolidation for water and its loading efficiency are two important physical parameters controlling consolidation behavior. With respect to the same soil texture, the coefficient of consolidation for water increases with an increase in initial water saturation, taking a value approximately four to five orders of magnitude greater in saturated soils than that in unsaturated ones. For a given initial water saturation, the rate of dissipation of excess pore water pressure is smallest in clay, followed by silty clay, silty clay loam, sandy clay, clay loam, silt loam, loam, sandy clay loam, sandy loam, loamy sand, and sand. A comparative study shows that in the early stage of consolidation, unsaturated soils bear smaller excess pore water pressure, but its dissipation is completed faster in saturated soils. The loading efficiency for water exhibits a concave upward relationship with initial water saturation in silty clay and clay, whereas a positively-correlated relationship between the efficiency and initial water saturation is observed in other soil textures. Unlike saturated soils, a considerable amount of total settlement is shown to occur immediately after application of external loading.

UR - http://www.scopus.com/inward/record.url?scp=84928883751&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84928883751&partnerID=8YFLogxK

U2 - 10.1016/j.advwatres.2015.04.004

DO - 10.1016/j.advwatres.2015.04.004

M3 - Article

VL - 82

SP - 51

EP - 69

JO - Advances in Water Resources

JF - Advances in Water Resources

SN - 0309-1708

ER -