A consolidation model for lumpy composite soils in open-pit mining

X. S. Shi (Lead / Corresponding author), I. Herle, D. Muir Wood

Research output: Contribution to journalArticle

  • 7 Citations

Abstract

In open-pit coal mining, the excavated clayey cover is dumped without any compaction to form a landfill with a relatively open structure. In this type of material, water flowing through the landfills prefers the inter-lump voids, which have a permeability significantly higher than the clay lumps. With increasing time, the lumps in the upper layer May be partially transformed into a reconstituted soil, occupying the inter-lump voids with consequent decrease in permeability of the landfill. In the study presented here, a consolidation model is proposed based on the double porosity concept and the homogenisation theory. The analysis follows these steps: step 1, a representative volume of lumpy composite soils is divided into four parts and the governing differential equations are formulated based on conservation of mass; step 2, the inter-lump porosity for the lumpy composite structure is formulated as a function of the overall porosity and the porosity of its constituents; step 3, to account for stress (strain) concentrations within the lumpy composite material, a homogenisation relation is used based on analysis of the soil structure; step 4, the hydraulic conductivities of the inter-lump material (lumps) and intra-lump material (reconstituted soil) are approximated by the same set of parameters; step 5, for the lumpy soil, a new relationship between the strains and the absolute velocities of the solid skeleton is proposed, which eliminates the influence of the rigid displacement of the lumps. The model simulations are compared with experimental data, indicating that the proposed model can well represent the consolidation curves of the lumpy composite soil observed in the laboratory.

LanguageEnglish
Pages189-204
Number of pages16
JournalGeotechnique
Volume68
Issue number3
Early online date12 Feb 2018
DOIs
Publication statusPublished - 1 Mar 2018

Fingerprint

Open pit mining
Consolidation
consolidation
Soils
porosity
Composite materials
Porosity
landfill
Land fill
soil
void
permeability
soil structure
coal mining
skeleton
Hydraulic conductivity
hydraulic conductivity
Composite structures
compaction
Coal mines

Keywords

  • Clays
  • Compressibility
  • Consolidation
  • Finite-element modelling
  • Landfills
  • Permeability

Cite this

Shi, X. S. ; Herle, I. ; Muir Wood, D. / A consolidation model for lumpy composite soils in open-pit mining. In: Geotechnique. 2018 ; Vol. 68, No. 3. pp. 189-204.
@article{ed09d6737d0543febd55b536b4741922,
title = "A consolidation model for lumpy composite soils in open-pit mining",
abstract = "In open-pit coal mining, the excavated clayey cover is dumped without any compaction to form a landfill with a relatively open structure. In this type of material, water flowing through the landfills prefers the inter-lump voids, which have a permeability significantly higher than the clay lumps. With increasing time, the lumps in the upper layer May be partially transformed into a reconstituted soil, occupying the inter-lump voids with consequent decrease in permeability of the landfill. In the study presented here, a consolidation model is proposed based on the double porosity concept and the homogenisation theory. The analysis follows these steps: step 1, a representative volume of lumpy composite soils is divided into four parts and the governing differential equations are formulated based on conservation of mass; step 2, the inter-lump porosity for the lumpy composite structure is formulated as a function of the overall porosity and the porosity of its constituents; step 3, to account for stress (strain) concentrations within the lumpy composite material, a homogenisation relation is used based on analysis of the soil structure; step 4, the hydraulic conductivities of the inter-lump material (lumps) and intra-lump material (reconstituted soil) are approximated by the same set of parameters; step 5, for the lumpy soil, a new relationship between the strains and the absolute velocities of the solid skeleton is proposed, which eliminates the influence of the rigid displacement of the lumps. The model simulations are compared with experimental data, indicating that the proposed model can well represent the consolidation curves of the lumpy composite soil observed in the laboratory.",
keywords = "Clays, Compressibility, Consolidation, Finite-element modelling, Landfills, Permeability",
author = "Shi, {X. S.} and I. Herle and {Muir Wood}, D.",
note = "No funding mentioned",
year = "2018",
month = "3",
day = "1",
doi = "10.1680/jgeot.16.P.054]",
language = "English",
volume = "68",
pages = "189--204",
journal = "Geotechnique",
issn = "0016-8505",
publisher = "Thomas Telford Ltd.",
number = "3",

}

A consolidation model for lumpy composite soils in open-pit mining. / Shi, X. S. (Lead / Corresponding author); Herle, I.; Muir Wood, D.

In: Geotechnique, Vol. 68, No. 3, 01.03.2018, p. 189-204.

Research output: Contribution to journalArticle

TY - JOUR

T1 - A consolidation model for lumpy composite soils in open-pit mining

AU - Shi, X. S.

AU - Herle, I.

AU - Muir Wood, D.

N1 - No funding mentioned

PY - 2018/3/1

Y1 - 2018/3/1

N2 - In open-pit coal mining, the excavated clayey cover is dumped without any compaction to form a landfill with a relatively open structure. In this type of material, water flowing through the landfills prefers the inter-lump voids, which have a permeability significantly higher than the clay lumps. With increasing time, the lumps in the upper layer May be partially transformed into a reconstituted soil, occupying the inter-lump voids with consequent decrease in permeability of the landfill. In the study presented here, a consolidation model is proposed based on the double porosity concept and the homogenisation theory. The analysis follows these steps: step 1, a representative volume of lumpy composite soils is divided into four parts and the governing differential equations are formulated based on conservation of mass; step 2, the inter-lump porosity for the lumpy composite structure is formulated as a function of the overall porosity and the porosity of its constituents; step 3, to account for stress (strain) concentrations within the lumpy composite material, a homogenisation relation is used based on analysis of the soil structure; step 4, the hydraulic conductivities of the inter-lump material (lumps) and intra-lump material (reconstituted soil) are approximated by the same set of parameters; step 5, for the lumpy soil, a new relationship between the strains and the absolute velocities of the solid skeleton is proposed, which eliminates the influence of the rigid displacement of the lumps. The model simulations are compared with experimental data, indicating that the proposed model can well represent the consolidation curves of the lumpy composite soil observed in the laboratory.

AB - In open-pit coal mining, the excavated clayey cover is dumped without any compaction to form a landfill with a relatively open structure. In this type of material, water flowing through the landfills prefers the inter-lump voids, which have a permeability significantly higher than the clay lumps. With increasing time, the lumps in the upper layer May be partially transformed into a reconstituted soil, occupying the inter-lump voids with consequent decrease in permeability of the landfill. In the study presented here, a consolidation model is proposed based on the double porosity concept and the homogenisation theory. The analysis follows these steps: step 1, a representative volume of lumpy composite soils is divided into four parts and the governing differential equations are formulated based on conservation of mass; step 2, the inter-lump porosity for the lumpy composite structure is formulated as a function of the overall porosity and the porosity of its constituents; step 3, to account for stress (strain) concentrations within the lumpy composite material, a homogenisation relation is used based on analysis of the soil structure; step 4, the hydraulic conductivities of the inter-lump material (lumps) and intra-lump material (reconstituted soil) are approximated by the same set of parameters; step 5, for the lumpy soil, a new relationship between the strains and the absolute velocities of the solid skeleton is proposed, which eliminates the influence of the rigid displacement of the lumps. The model simulations are compared with experimental data, indicating that the proposed model can well represent the consolidation curves of the lumpy composite soil observed in the laboratory.

KW - Clays

KW - Compressibility

KW - Consolidation

KW - Finite-element modelling

KW - Landfills

KW - Permeability

UR - http://www.scopus.com/inward/record.url?scp=85042018702&partnerID=8YFLogxK

U2 - 10.1680/jgeot.16.P.054]

DO - 10.1680/jgeot.16.P.054]

M3 - Article

VL - 68

SP - 189

EP - 204

JO - Geotechnique

T2 - Geotechnique

JF - Geotechnique

SN - 0016-8505

IS - 3

ER -