Quantifying vertical stress transmission and compaction-induced soil structure using sensor mat and X-ray computed tomography

Muhammad Naveed*, Per Schjonning, Thomas Keller, Lis W. de Jonge, Per Moldrup, Mathieu Lamande

*Corresponding author for this work

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Accurate estimation of stress transmission in soil and quantification of compaction-induced soil pore structure is important for efficient soil use and management. Continuum mechanics have so far mostly been applied for agricultural soils, even if topsoil structure is aggregated due to regular tillage. In this study, partially confined uniaxial compression tests were carried out on intact topsoil columns placed on subsoil columns. Two methods were employed for estimation of stress transmission in soil: (i) soil deformation patterns were quantified using X-ray CT and converted to stress distributions, and (ii) a tactile sensor mat was employed for measuring stresses at the interface of the topsoil and subsoil columns. The resulting soil pore structure under applied stresses was quantified using X-ray CT and by air-permeability measurements. In topsoil discrete stress transmission patterns were observed at 275 kPa applied stress, whereas continuum-like stress transmission was observed at 620 kPa. At the interface of topsoil and subsoil, discrete stress transmission patterns were observed at all applied stresses ranging from 68 to 620 kPa, but it was less discrete as we moved from lower to higher applied stresses. Our results imply that at lower stresses the stress transmission in arable soil was discrete because the applied load was mainly transmitted through chain of aggregates. At higher applied stresses the soil] aggregates deformed and to a larger degree resembled a continuous material where continuum-like stress transmission patterns were observed. We found that continuum stress transmission patterns were well simulated with models based on the elasticity theory (e.g., Boussinesq, 1885) compared to discrete stress transmission patterns. The soil pore structure was affected by increasing applied stresses. Total porosity was reduced 5-16% and macroporosity (pores > 0.5 mm) 50-85% at 620 kPa for topsoils. For subsoils - serving here as the material underlying the topsoil tests columns - only a small decrease was observed in both total porosity and macroporosity. Air permeability was reduced 55-80% for topsoils and 10-20% for subsoils at 620 kPa stress. Crown Copyright (C) 2015 Published by Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)110-122
Number of pages13
JournalSoil & Tillage Research
Volume158
Early online date28 Dec 2015
DOIs
Publication statusPublished - May 2016

Keywords

  • Soil compaction
  • Stress transmission
  • Soil deformation
  • Soil structure
  • SUBSOIL COMPACTION
  • LABORATORY MEASUREMENTS
  • INFLATION PRESSURE
  • AIR PERMEABILITY
  • IMAGE-ANALYSIS
  • GAS-TRANSPORT
  • WHEEL LOAD
  • IMPACT
  • DEFORMATION
  • PARAMETERS

Cite this

Quantifying vertical stress transmission and compaction-induced soil structure using sensor mat and X-ray computed tomography. / Naveed, Muhammad; Schjonning, Per; Keller, Thomas; de Jonge, Lis W.; Moldrup, Per; Lamande, Mathieu.

In: Soil & Tillage Research, Vol. 158, 05.2016, p. 110-122.

Research output: Contribution to journalArticle

Naveed, Muhammad ; Schjonning, Per ; Keller, Thomas ; de Jonge, Lis W. ; Moldrup, Per ; Lamande, Mathieu. / Quantifying vertical stress transmission and compaction-induced soil structure using sensor mat and X-ray computed tomography. In: Soil & Tillage Research. 2016 ; Vol. 158. pp. 110-122.
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AU - Naveed, Muhammad

AU - Schjonning, Per

AU - Keller, Thomas

AU - de Jonge, Lis W.

AU - Moldrup, Per

AU - Lamande, Mathieu

N1 - This work was part of project stress–strain behaviour of agricultural soils: toward new approaches (StressSoil) funded by the Danish Council for Independent Research, Technology and Production Sciences.

PY - 2016/5

Y1 - 2016/5

N2 - Accurate estimation of stress transmission in soil and quantification of compaction-induced soil pore structure is important for efficient soil use and management. Continuum mechanics have so far mostly been applied for agricultural soils, even if topsoil structure is aggregated due to regular tillage. In this study, partially confined uniaxial compression tests were carried out on intact topsoil columns placed on subsoil columns. Two methods were employed for estimation of stress transmission in soil: (i) soil deformation patterns were quantified using X-ray CT and converted to stress distributions, and (ii) a tactile sensor mat was employed for measuring stresses at the interface of the topsoil and subsoil columns. The resulting soil pore structure under applied stresses was quantified using X-ray CT and by air-permeability measurements. In topsoil discrete stress transmission patterns were observed at 275 kPa applied stress, whereas continuum-like stress transmission was observed at 620 kPa. At the interface of topsoil and subsoil, discrete stress transmission patterns were observed at all applied stresses ranging from 68 to 620 kPa, but it was less discrete as we moved from lower to higher applied stresses. Our results imply that at lower stresses the stress transmission in arable soil was discrete because the applied load was mainly transmitted through chain of aggregates. At higher applied stresses the soil] aggregates deformed and to a larger degree resembled a continuous material where continuum-like stress transmission patterns were observed. We found that continuum stress transmission patterns were well simulated with models based on the elasticity theory (e.g., Boussinesq, 1885) compared to discrete stress transmission patterns. The soil pore structure was affected by increasing applied stresses. Total porosity was reduced 5-16% and macroporosity (pores > 0.5 mm) 50-85% at 620 kPa for topsoils. For subsoils - serving here as the material underlying the topsoil tests columns - only a small decrease was observed in both total porosity and macroporosity. Air permeability was reduced 55-80% for topsoils and 10-20% for subsoils at 620 kPa stress. Crown Copyright (C) 2015 Published by Elsevier B.V. All rights reserved.

AB - Accurate estimation of stress transmission in soil and quantification of compaction-induced soil pore structure is important for efficient soil use and management. Continuum mechanics have so far mostly been applied for agricultural soils, even if topsoil structure is aggregated due to regular tillage. In this study, partially confined uniaxial compression tests were carried out on intact topsoil columns placed on subsoil columns. Two methods were employed for estimation of stress transmission in soil: (i) soil deformation patterns were quantified using X-ray CT and converted to stress distributions, and (ii) a tactile sensor mat was employed for measuring stresses at the interface of the topsoil and subsoil columns. The resulting soil pore structure under applied stresses was quantified using X-ray CT and by air-permeability measurements. In topsoil discrete stress transmission patterns were observed at 275 kPa applied stress, whereas continuum-like stress transmission was observed at 620 kPa. At the interface of topsoil and subsoil, discrete stress transmission patterns were observed at all applied stresses ranging from 68 to 620 kPa, but it was less discrete as we moved from lower to higher applied stresses. Our results imply that at lower stresses the stress transmission in arable soil was discrete because the applied load was mainly transmitted through chain of aggregates. At higher applied stresses the soil] aggregates deformed and to a larger degree resembled a continuous material where continuum-like stress transmission patterns were observed. We found that continuum stress transmission patterns were well simulated with models based on the elasticity theory (e.g., Boussinesq, 1885) compared to discrete stress transmission patterns. The soil pore structure was affected by increasing applied stresses. Total porosity was reduced 5-16% and macroporosity (pores > 0.5 mm) 50-85% at 620 kPa for topsoils. For subsoils - serving here as the material underlying the topsoil tests columns - only a small decrease was observed in both total porosity and macroporosity. Air permeability was reduced 55-80% for topsoils and 10-20% for subsoils at 620 kPa stress. Crown Copyright (C) 2015 Published by Elsevier B.V. All rights reserved.

KW - Soil compaction

KW - Stress transmission

KW - Soil deformation

KW - Soil structure

KW - SUBSOIL COMPACTION

KW - LABORATORY MEASUREMENTS

KW - INFLATION PRESSURE

KW - AIR PERMEABILITY

KW - IMAGE-ANALYSIS

KW - GAS-TRANSPORT

KW - WHEEL LOAD

KW - IMPACT

KW - DEFORMATION

KW - PARAMETERS

U2 - 10.1016/j.still.2015.12.006

DO - 10.1016/j.still.2015.12.006

M3 - Article

VL - 158

SP - 110

EP - 122

JO - Soil & Tillage Research

JF - Soil & Tillage Research

SN - 0167-1987

ER -