Measurement of Hydraulic Conductivity of Partially Saturated Soils

Hamilton, J. J.; Daniel, David E.; Olson, Roy E.

doi:10.1520/stp28324s

Cited by 40 publications

(25 citation statements)

References 7 publications

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“…Hamilton et al 1981;Krisdani et al 2009;Ng and Leung 2012). Profiles of water content and suction at several points along the specimen are normally monitored at fixed time intervals in order to compute the flow rate, hydraulic gradient and permeability at different suctions.…”

Section: Testing Methodsmentioning

confidence: 99%

Effects of grass roots on soil-water retention curve and permeability function

2017

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The effects of Vetiver grass (Chrysopogon zizanioides) roots on the soil-water retention curves (SWRCs), permeability (k) function, and saturated permeability, ksat, have been investigated on clayey sand (SC) and low-plasticity silt (ML). For ML soil, when the root biomass per soil volume was lower than 6.5 kg/m3, the saturated permeability increased, the air-entry suction decreased slightly, and the SWRC became steeper with increasing root contents, probably due to the formation of cracks caused by wetting and drying cycles during the plant growing period. Nevertheless, roots appeared to decrease the saturated permeability and increase the air-entry suction of ML soil, after reaching this threshold with a root content of about 6.5 kg/m3 as roots occupied the macropores and tended to suppress cracks and swelling. For SC soil for all root contents, only a slight variation of the saturated permeability with root content could be observed for the upper bounds on saturated permeability. However, the lower bounds on saturated permeability appeared to decrease as root content increased. It has also been shown that for a suction range beyond 30 kPa, the influence of roots on permeability appeared to be less significant.

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Section: Testing Methodsmentioning

confidence: 99%

Effects of grass roots on soil-water retention curve and permeability function

2017

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“…Several investigators have determined the unsaturated coefficient of permeability of compacted specimens in the laboratory following the wetting front using the IPM (Hamilton et al 1979;Merdink et al 1996). The IPM requires measurements of water content and matric suction to determine the unsaturated coefficient of permeability.…”

Section: Permeameter and The Instantaneous Profile Methodsmentioning

confidence: 99%

“…Richards and Weeks (1953) originally described this method. Several other investigators used this technique (Klute 1972;Hamilton et al 1979;Meerdink et al 1996).…”

Section: Introductionmentioning

confidence: 99%

A modified permeameter for determination of unsaturated coefficient of permeability

2006

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The design details of a modified permeameter used for determining the unsaturated coefficient of permeability of tailings are presented in this Paper. This permeameter can accommodate a large tailings specimen, 200 · 200 · 400 mm high, and uses the Instantaneous Profile Method (IPM) to determine the variation of unsaturated coefficient of permeability with respect to soil suction using a single specimen. The soil-water characteristic curve data can also be simultaneously determined from the modified permeameter. The key design features in comparison to a conventional permeameter include the provision of adjustable sensors that move along with the tailings as it settles due to desaturation during the testing period. The advantages of using a modified permeameter in the determination of the coefficient of permeability of unsaturated tailings are also discussed in this paper. Tests were carried out by providing suction using hanging column technique in the suction range of 0-10 kPa. Such an apparatus can easily be modified to accommodate higher suction values.

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“…The IPM applied to diŠerent surface water ‰ow conditions (evaporation and inˆltration) has been used by many researchers (Wind, 1968;Vachaud et al, 1974;Hamilton et al, 1981;Daniel, 1983;Ed Diny, 1993;Tamari et al, 1993;Chiu and Shackelford, 1998;Gaidi, 2002;Arya 2002) to estimate the retention and conductivity curves for diŠerent soils in a large water content range. The IPM is an unsteady-state method.…”

Section: Ipm (Inˆltration In a Vertical Column Of Soil)mentioning

confidence: 99%

Measurements of Unsaturated Hydraulic Conductivity Functions of Two Fine-Grained Materials

Taïbi

Bicalho

Sayad-Gaidi

et al. 2009

Soils and Foundations

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Water unsaturated hydraulic conductivity (kw) functions of two remoldedˆne-grained materials were measured over a wide range of degrees of saturation (Sr) with two methods. The instantaneous proˆle method (IPM) was used for Sr À50z. An original vapor equilibration method (also known as the vapor equilibrium technique, VET) was used for Sr º50z. Both materials compacted at the standard Proctor optimum water content and maximum density, have saturated hydraulic conductivities (ksat)º10-7 m/s. The VET couples the total soil suction (s) control from desiccators with saturated salt solutions with water mass measurements from a digital laboratory balance. The kw measurements of the two techniques are consistent and complementary. The eŠect of hysteresis on the kw functions at higher s values was also investigated. The experimental results suggest that the hysteretic eŠect on the kw-Sr and kw-s relationships cannot be neglected, and that the measured kw are signiˆcantly dependent on the initial Sr. The VET tests on the specimens that were initially dried give the lowest values of kw and the tests on the specimens that were initially saturated give the highest values of kw. The relative hydraulic conductivity values are very small (krwº2×10 -5 ) in this saturation range (Srº50z) for the tested materials.

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Measurement of Hydraulic Conductivity of Partially Saturated Soils

Cited by 40 publications

References 7 publications

Effects of grass roots on soil-water retention curve and permeability function

Effects of grass roots on soil-water retention curve and permeability function

A modified permeameter for determination of unsaturated coefficient of permeability

Measurements of Unsaturated Hydraulic Conductivity Functions of Two Fine-Grained Materials

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