Calculation of the compression index and precompression stress from soil compression test data

Gregory, Andrew S.; Whalley, W. R.; Watts, C. W.; Bird, N. R. A.; Hallett, Paul D.; Whitmore, A. P.

doi:10.1016/j.still.2005.06.012

Cited by 124 publications

(118 citation statements)

References 15 publications

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“…6). Compression index tends to increase for soils with greater clay content due to greater plasticity and void ratios (Gregory et al 2006). Moreover, the clay loam soil had greater resilience to compression (Figs.…”

Section: Discussionmentioning

confidence: 96%

Plant exudates improve the mechanical conditions for root penetration through compacted soils

et al. 2017

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Background and aim Plant exudates greatly affect the physical behaviour of soil, but measurements of the impact of exudates on compression characteristics are missing. Our aim is to provide these data and explore how plant exudates may enhance the restructuring of compacted soils following cycles of wetting and drying. Methods Two soils were amended with Chia (Salvia hispanica) seed exudate at 5 concentrations, compacted in cores to 200 kPa stress (equivalent to tractor stress), equilibrated to −50 kPa matric potential, and then compacted to 600 kPa (equivalent to axial root stress) followed by 3 cycles of wetting and drying and recompression to 600 kPa at −50 kPa matric potential. Penetration resistance (PR), compression index (C C ) and pore characteristics were measured at various steps.

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Section: Discussionmentioning

confidence: 96%

Plant exudates improve the mechanical conditions for root penetration through compacted soils

et al. 2017

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“…The curves simulated cover a wide range of soil compression curves, such as those obtained for soil samples in compression tests under different soil bulk densities, textures, and moisture contents (Arvidsson and Keller, 2004;Imhoff et al, 2004;Gregory et al, 2006;Cavalieri et al, 2008;Ajayi et al, 2009;Saffih-Hdadi et al, 2009;Ajayi et al, 2013;An et al, 2015).…”

Section: Simulated Soil Compression Curvesmentioning

confidence: 99%

“…The studies of Arvidsson and Keller (2004), Gregory et al (2006), Cavalieri et al (2008), Ajayi et al (2013), and An et al (2015) demonstrated there are variations in the methods used for determination of the σ p and that the shape of curve is an important source of variation of indices (σ p , C s , C c ) extracted from the soil compression curve, showing that further studies are required. However, these studies have in common many soils, moisture contents, textures, and different conditions in soil physical properties, which makes it hard to define the parameters of the compression curve for a specific study and more accurate analysis.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Methods for Determining Precompression Stress Based on Computational Simulation

Silva

Lima

2016

Rev. Bras. Ciênc. Solo

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There are many methods for determining precompression stress (σ p ), whose value is affected by the slope of the soil compression curve. This study was designed to evaluate the hypothesis that for a certain compression curve all methods used to determine σ p present the same value and accuracy. The aim of this study was to compare the accuracy and the relationship among seven of these methods by computational simulation of soil compression curves under nine scenarios. The following methods were used: Casagrande, Pacheco Silva, intersection of the initial void ratio with the virgin compression line (VCLzero), and the regression methods based on 2 (reg1), 3 (reg2), 4 (reg3), and 5 (reg4) points for modeling the elastic curve. Under each scenario, created by combining the swelling and the compression indices, 1,000 compression curves were computationally simulated via the Monte Carlo method. Subsequently, 95 % percentile confidence intervals were built using the 1,000 estimates of σ p from each method under each scenario. Most of the differences among the methods were detected under scenarios consisting of high swelling and low compression indices. In general, Casagrande, Pacheco Silva, and reg4 were strongly correlated and presented the highest values of σ p , as well as similar variability. The latter two can be considered as alternatives to the standard method of Casagrande, except for Pacheco Silva when the curve has a low compression index (≤0.2) and from medium to high swelling index (≥0.025), for which differences (p<0.05) were detected.

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“…The soil compression curve or stress-deformation curve can be described as a measure of soil deformation under given external loads (Holtz & Kovacz, 1981) (Figure 4) and defines the relationship between the logarithm of applied normal stress on the top of the sample and some parameter related to the packing state of soil; for example soil void ratio or soil bulk density (Casagrande, 1936;Larson et al, 1980;Holtz & Kovacs, 1981;Horn, 1988;Dias Junior & Pierce, 1995). This curve is divided into two regions so-called: a region of plastic and unrecoverable deformation called the virgin compression curve, and a region of small, elastic and recoverable deformation called the secondary compression curve (Larson et al, 1980;Holtz & Kovacs, 1981;Dias Junior & Pierce, 1995;Gregory et al, 2006). The point that separates these two regions in a compression curve is the precompression stress or preconsolidation pressure (σp) depending on if air or water is being eliminated from the soil, and can be variously defined.…”

Section: Soil Compressive Behavior and Load Bearing Capacity Modelsmentioning

confidence: 99%

Interrelationships Among Weed Management in Coffee Plantation and Soil Physical Quality

Araújo-Junior¹,

Dias²,

Alcântara³

et al. 2012

Weed Control

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Calculation of the compression index and precompression stress from soil compression test data

Cited by 124 publications

References 15 publications

Plant exudates improve the mechanical conditions for root penetration through compacted soils

Plant exudates improve the mechanical conditions for root penetration through compacted soils

Comparison of Methods for Determining Precompression Stress Based on Computational Simulation

Interrelationships Among Weed Management in Coffee Plantation and Soil Physical Quality

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