Critical-state Behaviour of an Agricultural Soil

Adams, B. A.; Wulfsohn, D.

doi:10.1006/jaer.1998.0286

Cited by 11 publications

(7 citation statements)

References 4 publications

(4 reference statements)

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“…The compression index of a second group of soils increased with matric suction. This was reported for loess soil (Adams and Wulfsohn, 1998;Kogho et al, 2001;Wang et al, 2002;Futai and Almeida, 2005) and for sandy soils (Futai and Almeida, 2005). Our results tend to agree with the second group.…”

Section: Variation Of Compression Index With Soil Texturesupporting

confidence: 91%

Quantifying the effect of matric suction on the compressive properties of two agricultural soils using an osmotic oedometer

et al. 2010

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The compaction of cultivated soils by agricultural machines considerably affects both the structure and physical properties of soil, thus having a major impact on crop production and the environment. Soil mechanical resistance is highly variable both in time and space because it depends on soil texture, soil porosity and soil water state (matric suction). This paper is devoted to the effect of soil matric suction on the compression index C c , which is one of the mechanical parameters that describes the soil mechanical resistance to compression. We performed oedometer compression tests to study the compression index of a loamy soil and a sandy clay, with matric suction control, by using the osmotic technique. Soil samples were prepared by compacting soil passed through a 2 mm sieve at dry bulk densities of 1.1 and 1.45 Mg m −3 . The mechanical stress and matric suction ranges considered corresponded to field condition, with vertical stress less than 800 kPa and matric suction less than 200 kPa. The results show that the compression index C c was constant or changed little with matric suctions for the two soils at different initial densities. For the loamy soil, the average compression index C c equals 0.73 for an initial bulk density of 1.1 Mg m −3 and 0.41 for 1.45 Mg m −3 for matric suction higher than 20 kPa. For the sandy clay, the average compression index C c is 0.35. From a practical point of view, our study shows that the mathematical determination of mechanical parameters should be standardized due to the S-shaped compression curves that may significantly impact the compression index estimation. The observation of constant compression index with matric suction is a useful result for modelling soil strain due to traffic and predicting the compaction of cultivated soils.

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Section: Variation Of Compression Index With Soil Texturesupporting

confidence: 91%

Quantifying the effect of matric suction on the compressive properties of two agricultural soils using an osmotic oedometer

et al. 2010

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“…Batch soil samples were prepared by spraying fine droplets of a predetermined amount of water with air dried soil that passed through sieve size 10 (2-mm opening). Soil specimens (length to diameter ratios of 0.4 for soilwater characteristic specimens and 2 for uniaxial compression and triaxial tests) were formed by compacting soil samples using a teflon-capped graduated piston in a cylindrical mould (Adams, 1996). A typical triaxial specimen (140-mm length by 70-mm diameter) was formed by sequential compaction of five 28-mm layers of predetermined amounts of soil.…”

Section: Materials and Experimental Methodsmentioning

confidence: 99%

“…Special low and high air discs were integrated into the triaxial cell. The modifications (Adams, 1996;Wulfsohn et al, 1994) permit measurement and control of matric suction and the measurement of both pore air and pore water volume changes. Each test specimen was enclosed within a composite membrane made of a slotted aluminium foil sandwiched between two rubber membranes to reduce diffusion of air between the specimen and cell water.…”

Section: Materials and Experimental Methodsmentioning

confidence: 99%

“…They noted that the precompression stress is exceeded at about the same time the value of the negative pore water pressure is exceeded. Adams (1996) and Wulfsohn et al (1994Wulfsohn et al ( , 1996 observed significant changes in matric suction when the applied load exceeded some transition stress related to the specimen matric suction.…”

Section: Effect Of Matric Suction On Soil Behaviourmentioning

confidence: 99%

See 1 more Smart Citation

Variation of the critical‐state boundaries of an agricultural soil

Adams

Wulfsohn

1997

European J Soil Science

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The critical-state theory can be applied profitably to analyse the mechanical behaviour of agricultural soil. Critical-state parameters and other soil properties are affected by the microstructure and unsaturated nature of agricultural soils. We determined the critical-state boundaries of an agricultural soil in both saturated and unsaturated triaxial tests and examined the effects of matric suction and initial structure on critical-state boundaries. On the compression plane, the presence of air and matric suction in the pores of unsaturated soil significantly affected critical-state boundaries by increasing compressibility, A.On the deviatoric stress-mean net stress plane, the strength increased with matric suction. On this plane, the critical-state lines for the unsaturated tests had non-zero intercepts. For a given soil structure, the frictional parameter M remained fairly constant with matric suction change. However, a change in the initial microstructure resulted in a change in M, causing the position of the critical-state line to 'pivot' in state space.

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“…Cylindrical specimens of 70 mm diameter (D);140 mm length (¸) were formed by compacting the sample in five uniform layers in a specially designed mould. 39 The approximate bulk density, degree of saturation and matric suction of the resulting specimens were 1)2 Mg/m, 32% and 50 kPa, respectively.…”

Section: Evaluation Of Unsaturated Triaxial Testing Proceduresmentioning

confidence: 99%