An Examination of the Fall‐cone Method for the Determination of Some Strength Properties of Remoulded Agricultural Soils

Towner, G. D.

doi:10.1111/j.1365-2389.1973.tb02314.x

Cited by 44 publications

(15 citation statements)

References 2 publications

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“…The lower plastic limit (wPL) was determined by rolling threads of soil until cracks just appeared (British Standards, 1975), and the upper plastic limit or liquid limit (wLL) was determined by the fall-cone method (British Standards, 1975). These limits correspond to rapid, undrained shear strengths, T,, of approximately 140 kPa and 1.4 kPa, respectively (Towner, 1973).…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Soil mechanical properties as influenced by exchangeable cations

Dexter

Chan²

1991

Journal of Soil Science

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The tensile strengths of dried, undisturbed aggregates and of dried, artificial aggregates and the shear strengths of freshly-moulded, moist soils were investigated as functions of their contents of exchangeable cations.Tensile strength increased with increasing exchangeable sodium and decreased with increasing exchangeable calcium. Shear strength of moist soil, as assessed through the Atterberg limits, increased with increasing exchangeable calcium, potassium and sodium. The influence of exchangeable magnesium was variable in that it tended to increase the tensile strength of the soils when dry, whereas it tended to decrease the shear strength of one of the sets of soils in the moist state.It is concluded that the exchangeable cations which give rise to greater repulsion between, and dispersion of, clay particles in water also give rise to greater strength in the dried soil. It is proposed that this is because greater particle repulsion in the soil water during dryingenables particle rearrangements to take place more readily and this results in denser packing arrangements and increased strength. I N T R O D U C T I O NSoil strength is controlled by a number of factors including the properties of the particle surfaces which are in contact or near contact. The properties of the particle surfaces are strongly dependent on the types of ions adsorbed onto them. Many of these ions are described as exchangeable because they can be replaced by other ions. Richards (1953) showed that, for briquets of soil which had been prepared by moulding when moist and then air-drying, samples which were sodic (with a predominance of exchangeable Na ions) had greater strength, as measured by the modulus of rupture test, than samples which were calcic (with a predominance of exchangeable Ca ions). Similarly, Warkentin & Yong (1962) showed that the shear strength of Na montmorillonite was greater than that of Ca montmorillonite.Reeve et al. (1954) showed that modulus of rupture increased linearly with increasing exchangeable Na, but that there was no significant effect with K. An increase in modulus of rupture with increasing exchangeable Na was also shown by Gerard (1965).The effects of a wider range of cations on the tensile strength of oriented montmorillonite films were investigated by Dowdy & Larson (1971). In general, strength decreased in the order:Fe > K 2 Na > A1 > Ca. It was thought that the mechanism of bonding with Fe was different from that with the other ions.All of the above results are for relatively dry soils or clays (drier than around -10 MPa total water potential). At the other epd of the scale, at saturation, or in the presence of free water, clay particles may repel one another and disperse. When dispersion occurs, the strength of the material

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Section: Mechanical Propertiesmentioning

confidence: 99%

Soil mechanical properties as influenced by exchangeable cations

Dexter

Chan²

1991

Journal of Soil Science

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“…The details of this apparatus and the method of use are also described by Towner (1973). The cone penetration results are shown in Fig.…”

Section: Experimental Methodsmentioning

confidence: 98%

The Assessment of Soil Texture From Soil Strength Measurements

Towner

1974

Journal of Soil Science

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Soil texture is usually assessed by either the manipulation of the field soil in the hand or by a particle size analysis of the dispersed soil. These two methods are often regarded uncritically as alternatives, and this paper stresses the point of view that the hand manipulation method is the preferred one, because the particle size analysis method depends on the establishment of relevant correlations. However, the subjective nature of the first method is admitted, and the paper describes an attempt to devise an objective test based on the elements of the hand assessment. From the observation that one senses the reaction of the soil to compressive and shearing forces during an assessment by hand it is suggested that some measure of soil strength might be used as an index of texture.The strength of twenty-three soils was measured over a range of water contents using the fall-cone penetrometer. The curves representing the relationship between the strengths and the water contents were all of a similar shape and tended to form a regular array, with the lighter soils at the low water content end of the scale and the heavier soils at the higher end. They showed that the strength of a given soil was very sensitive to water content.It was concluded that the separation of the soils into the broad textural classes was made mainly from measurements of the strengths of the wetted soils, but that the more detailed descriptions, including for example, specification of the grade of the sand, required in addition an estimation of the sizes of the particles obtained by feeling them between the fingers. As a corollary, these finer divisions are not related to soil strength, and thus are dubious indications of heaviness or lightness.

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“…A range of cones with different weights (24, 80, 130, 180 and 230 g) and angles (30° and 60°) were prepared and used on different targets. Depth of cone penetration was read on the instrument's dial gauge and converted to surface shear strength using equations given in the literature (Hansbo, 1957;Towner, 1973).…”

Section: Fall-cone Penetrometermentioning

confidence: 99%

Crater formation in soils by raindrop impact

Ghadiri

2004

Earth Surf Processes Landf

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The process of crater formation by the impact of water drops on soil, sand and various other target material was studied. Craters of various shapes and sizes were observed on different target materials or conditions, ranging from circumferential depression to completely hemispherical shape. Crater shape was dependent upon target material, its flow stress or shear strength and the presence and thickness of water on the surface. Between 5 and 22 per cent of impact energy was spent on cratering, but the relationship between crater volume and kinetic energy of a raindrop was curvilinear, indicating a lower efficiency of impact energy in removing target material as the energy increases. Impact impulse, on the other hand, showed a more linear relationship with crater volume, and the ratio of impulse over crater volume (I/V) remained constant for the entire range of drop sizes, impact velocities, and surface conditions used in this study. Surface shear strength, represented by the penetration depth of fall-cone penetrometer, appeared to be a key factor involved in this process. An equation was developed which related crater volume to cone penetration depth and impact impulse. Crater volume, which appeared to be a better indicator of the total amount of material dislodged by a raindrop than splash amount, can thus be predicted using this equation.

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An Examination of the Fall‐cone Method for the Determination of Some Strength Properties of Remoulded Agricultural Soils

Cited by 44 publications

References 2 publications

Soil mechanical properties as influenced by exchangeable cations

Soil mechanical properties as influenced by exchangeable cations

The Assessment of Soil Texture From Soil Strength Measurements

Crater formation in soils by raindrop impact

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