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H. Rahardjo - One of the best experts on this subject based on the ideXlab platform.

  • estimation of the air permeability function from the Soil Water Characteristic curve
    Engineering Geology, 2015
    Co-Authors: Qian Zhai, H. Rahardjo, Alfrendo Satyanaga
    Abstract:

    The multiphase flow (including liquid flow and air flow) in unsaturated Soil is related to many engineering problems such as contaminant transport, rainWater infiltration and Soil-Water evaporation. It is proven that Water flow in unsaturated Soil can be estimated using the concept of pore-size distribution function. Many models have been proposed to estimate the Water flow or Water permeability function, kw, from Soil-Water Characteristic curve (SWCC). On the other hand, a limited model has been proposed to estimate the air flow or air permeability function, ka, from SWCC. Most of the models used for the estimation of the air permeability functions are empirical and they are dependent on the empirical parameters. In this paper, the relative air coefficient of permeability was estimated using the concept of pore-size distribution function. In the method proposed in this paper, there was no empirical parameters adopted and the estimation results purely depended on the Soil-Water Characteristic curve. The p...

  • effect of range of Soil Water Characteristic curve measurements on estimation of permeability function
    Engineering Geology, 2015
    Co-Authors: Arezoo Rahimi, H. Rahardjo, E. C. Leong
    Abstract:

    Abstract The most commonly used indirect method to determine unsaturated permeability of Soil is to estimate the unsaturated permeability function from Soil–Water Characteristic curve and saturated permeability. The suction range that Soil–Water Characteristic curve (SWCC) can be measured in the laboratory depends on the type of equipment used for measurement. As the estimation models use the available measured SWCC data to obtain the unsaturated permeability function, the estimated permeability function can be affected by the number of measured data of SWCC and the suction range over which the SWCC data are measured. Therefore, there is a need to investigate the effect of the range of SWCC measurements on the estimation of unsaturated permeability function. In this study, the effect of the range of SWCC measurements is investigated through different estimation models that are based on four different best-fit Soil–Water Characteristic curve equations and three different relative permeability equations. It was found that the range of SWCC measurements greatly affect the estimated permeability functions. It was also found that the effect of the range of SWCC measurements is more significant than the selected best-fit SWCC equation used.

  • determination of Soil Water Characteristic curve variables
    Computers and Geotechnics, 2012
    Co-Authors: Qian Zhai, H. Rahardjo
    Abstract:

    Abstract Soil–Water Characteristic curve (SWCC) contains the fundamental information needed for describing the mechanical behavior of unsaturated Soil. Some parameters such as air-entry value, slope at the inflection point, residual Water content and residual suction are commonly used to describe the SWCC and other associated properties such as shear strength and permeability. Currently these parameters are determined using the graphical method which can be subjective and time consuming. Equations for determining these parameters are proposed and the relationships between SWCC parameters and fitting parameters are discussed in this paper. These equations can be used for computational analyses to replace the conventional graphical method in providing consistent results.

  • Soil–Water Characteristic curves of Singapore residual Soils
    Geotechnical & Geological Engineering, 2001
    Co-Authors: S. S. Agus, E. C. Leong, H. Rahardjo
    Abstract:

    Soil–Water Characteristic curves were obtained for a number of Singapore residual Soil samples. Soil samples were obtained from the two main residual Soil formations, the Jurong sedimentary formation and the Bukit Timah granitic formation, at various depths. The effect of weathering on the shape of the Soil–Water Characteristic curve is examined. As the test procedure in obtaining the Soil–Water Characteristic curve is tedious and time-consuming, empirical relationships based on multivariate analysis relating the parameters of the Fredlund and Xing (1994) Soil–Water Characteristic curve equation to basic Soil properties are suggested for the Singapore residual Soils. The multivariate equations were found to be suitable for providing a quick preliminary estimate of the Soil–Water Characteristic curve of Singapore residual Soils.

  • Soil Water Characteristic curves of singapore residual Soils
    Geotechnical and Geological Engineering, 2001
    Co-Authors: S. S. Agus, E. C. Leong, H. Rahardjo
    Abstract:

    Soil–Water Characteristic curves were obtained for a number of Singapore residual Soil samples. Soil samples were obtained from the two main residual Soil formations, the Jurong sedimentary formation and the Bukit Timah granitic formation, at various depths. The effect of weathering on the shape of the Soil–Water Characteristic curve is examined. As the test procedure in obtaining the Soil–Water Characteristic curve is tedious and time-consuming, empirical relationships based on multivariate analysis relating the parameters of the Fredlund and Xing (1994) Soil–Water Characteristic curve equation to basic Soil properties are suggested for the Singapore residual Soils. The multivariate equations were found to be suitable for providing a quick preliminary estimate of the Soil–Water Characteristic curve of Singapore residual Soils.

E. C. Leong - One of the best experts on this subject based on the ideXlab platform.

  • Modelling the effect of density on the unimodal Soil-Water Characteristic curve
    Geotechnique, 2017
    Co-Authors: M. Wijaya, E. C. Leong
    Abstract:

    Research has shown that the Soil-Water Characteristic curve (SWCC) is dependent on the density of the Soil; therefore, using a single SWCC based on one density is insufficient to describe the SWCC ...

  • equation for unimodal and bimodal Soil Water Characteristic curves
    Soils and Foundations, 2016
    Co-Authors: M. Wijaya, E. C. Leong
    Abstract:

    Abstract Soil–Water Characteristic curve (SWCC) data are usually curve fitted with an equation whose parameters were obtained by using optimization procedures. Due to the interdependency of the parameters in the SWCC equation, the parameters are non-unique and thus it is difficult to relate the parameters to other Soil properties. This becomes more prominent for bimodal SWCC equations which have more curve-fitting parameters. In order to overcome this limitation, a new equation for both unimodal and bimodal SWCCs is proposed. The new equation uses parameters that can be obtained graphically and no curve-fitting procedures are necessary. Hence, its parameters are unique. The proposed equation was shown to be accurate in representing both unimodal and bimodal SWCCs with several examples.

  • effect of range of Soil Water Characteristic curve measurements on estimation of permeability function
    Engineering Geology, 2015
    Co-Authors: Arezoo Rahimi, H. Rahardjo, E. C. Leong
    Abstract:

    Abstract The most commonly used indirect method to determine unsaturated permeability of Soil is to estimate the unsaturated permeability function from Soil–Water Characteristic curve and saturated permeability. The suction range that Soil–Water Characteristic curve (SWCC) can be measured in the laboratory depends on the type of equipment used for measurement. As the estimation models use the available measured SWCC data to obtain the unsaturated permeability function, the estimated permeability function can be affected by the number of measured data of SWCC and the suction range over which the SWCC data are measured. Therefore, there is a need to investigate the effect of the range of SWCC measurements on the estimation of unsaturated permeability function. In this study, the effect of the range of SWCC measurements is investigated through different estimation models that are based on four different best-fit Soil–Water Characteristic curve equations and three different relative permeability equations. It was found that the range of SWCC measurements greatly affect the estimated permeability functions. It was also found that the effect of the range of SWCC measurements is more significant than the selected best-fit SWCC equation used.

  • Effect of range of Soil–Water Characteristic curve measurements on estimation of permeability function
    Engineering Geology, 2015
    Co-Authors: Arezoo Rahimi, Harianto Rahardjo, E. C. Leong
    Abstract:

    Abstract The most commonly used indirect method to determine unsaturated permeability of Soil is to estimate the unsaturated permeability function from Soil–Water Characteristic curve and saturated permeability. The suction range that Soil–Water Characteristic curve (SWCC) can be measured in the laboratory depends on the type of equipment used for measurement. As the estimation models use the available measured SWCC data to obtain the unsaturated permeability function, the estimated permeability function can be affected by the number of measured data of SWCC and the suction range over which the SWCC data are measured. Therefore, there is a need to investigate the effect of the range of SWCC measurements on the estimation of unsaturated permeability function. In this study, the effect of the range of SWCC measurements is investigated through different estimation models that are based on four different best-fit Soil–Water Characteristic curve equations and three different relative permeability equations. It was found that the range of SWCC measurements greatly affect the estimated permeability functions. It was also found that the effect of the range of SWCC measurements is more significant than the selected best-fit SWCC equation used.

  • Soil–Water Characteristic curves of Singapore residual Soils
    Geotechnical & Geological Engineering, 2001
    Co-Authors: S. S. Agus, E. C. Leong, H. Rahardjo
    Abstract:

    Soil–Water Characteristic curves were obtained for a number of Singapore residual Soil samples. Soil samples were obtained from the two main residual Soil formations, the Jurong sedimentary formation and the Bukit Timah granitic formation, at various depths. The effect of weathering on the shape of the Soil–Water Characteristic curve is examined. As the test procedure in obtaining the Soil–Water Characteristic curve is tedious and time-consuming, empirical relationships based on multivariate analysis relating the parameters of the Fredlund and Xing (1994) Soil–Water Characteristic curve equation to basic Soil properties are suggested for the Singapore residual Soils. The multivariate equations were found to be suitable for providing a quick preliminary estimate of the Soil–Water Characteristic curve of Singapore residual Soils.

Delwyn G. Fredlund - One of the best experts on this subject based on the ideXlab platform.

  • State of Practice for use of the Soil-Water Characteristic Curve in Geotechnical Engineering
    Canadian Geotechnical Journal, 2019
    Co-Authors: Delwyn G. Fredlund
    Abstract:

    Routine geotechnical engineering practice has witnessed a significant increase in the usage of unsaturated Soil mechanics principles. Laboratory measurement of the Soil-Water Characteristic curve (...

  • Microporous Membrane Technology for Measurement of Soil-Water Characteristic Curve
    Geotechnical Testing Journal, 2012
    Co-Authors: Tomoyoshi Nishiumura, Delwyn G. Fredlund, Junichi Koseki, Harianto Rahardjo
    Abstract:

    High air entry ceramic disks are commonly used for the control of matric suction in triaxial and direct shear tests and in tests for obtaining the Soil-Water Characteristic curve. Geotechnical engineers have made increasing use of high air entry ceramic disks in order to measure or control matric suctions during unsaturated Soil testing. One of the limitations associated with the use of high air entry ceramic disks has been the time required in order for equilibrium conditions to be established across the disk. Improving the efficiency associated with establishing suction equilibrium is of considerable interest to geotechnical engineers. Pressure membrane technology involving the use of microporous membranes is one possible technology that could result in improved performance for the measurement or control of matric suctions. If microporous membrane technology can be used, the end result could provide considerable time and cost savings, particularly in the measurement of Soil-Water Characteristic curves (SWCCs). In this study, a new apparatus was developed to make use of a microporous membrane for the measurement of the SWCC with matric suction of up to 25 kPa. The maximum AEV (i.e., air-entry value) of the membrane is 250 kPa. This paper presents the results of laboratory SWCC measurements on several Soil types using pressure membrane technology. Comparisons are made between the Soil-Water Characteristic curves measured using a conventional pressure plate apparatus and those obtained from the new micro membrane apparatus.

  • Equations for the entire Soil-Water Characteristic curve of a volume change Soil
    Canadian Geotechnical Journal, 2008
    Co-Authors: Hung Q. Phamh.q. Pham, Delwyn G. Fredlund
    Abstract:

    Numerous curve-fitting equations have been proposed for Soil-Water Characteristic curves. While these equations have been of considerable value in geotechnical and geoenvironmental engineering, the equations are not able to adequately fit gravimetric Soil-Water Characteristic curve data over the entire range of Soil suction for a Soil that changes volume when suction is changed. Two new equations for the Soil-Water Characteristic curve are presented in this paper. One equation has curve-fitting parameters that bear a meaningful relationship to conventional physical Soil properties (e.g., air-entry value and residual Soil suction), but the equation is somewhat complex. The equation is particularly useful for sensitivity type studies when undertaking computer modeling. The other equation is relatively simple to use and is developed as a conventional curve-fitting equation. The two equations are used to best-fit several Soil datasets. Both equations perform well and can be used in research and engineering pr...

  • A study of hysteresis models for Soil-Water Characteristic curves
    Canadian Geotechnical Journal, 2005
    Co-Authors: Hung Q. Pham, Delwyn G. Fredlund, S. Lee Barbour
    Abstract:

    A review of hysteresis models for Soil-Water Characteristic curves is presented. The models can be categorized into two groups: (i) domain models (or physically based models) and (ii) empirical mod...

  • Measurement of Soil-Water Characteristic curves for fine-grained Soils using a small-scale centrifuge
    Canadian Geotechnical Journal, 2002
    Co-Authors: R. M. Khanzode, Sai K Vanapalli, Delwyn G. Fredlund
    Abstract:

    Considerably long periods of time are required to measure Soil-Water Characteristic curves using conventional equipment such as pressure plate apparatus or a Tempe cell. A commercially available, small-scale medical centrifuge with a swinging type rotor assembly was used to measure the Soil-Water Characteristic curves on statically compacted, fine-grained Soil specimens. A specimen holder was specially designed to obtain multiple sets of Water content versus suction data for measuring the Soil-Water Characteristic curve at a single speed of rotation of the centrifuge. The Soil-Water Characteristic curves were measured for three different types of fine-grained Soils. The three Soils used in the study were processed silt (liquid limit, wL = 24%; plasticity index, Ip = 0; and clay = 7%), Indian Head till (wL = 35.5%, Ip = 17%, and clay = 30%), and Regina clay (wL = 75.5%, Ip = 21%, and clay = 70%). The Soil-Water Characteristic curves for the above Soils were measured in 0.5, 1, and 2 days, respectively, usi...

S. S. Agus - One of the best experts on this subject based on the ideXlab platform.

  • Soil–Water Characteristic curves of Singapore residual Soils
    Geotechnical & Geological Engineering, 2001
    Co-Authors: S. S. Agus, E. C. Leong, H. Rahardjo
    Abstract:

    Soil–Water Characteristic curves were obtained for a number of Singapore residual Soil samples. Soil samples were obtained from the two main residual Soil formations, the Jurong sedimentary formation and the Bukit Timah granitic formation, at various depths. The effect of weathering on the shape of the Soil–Water Characteristic curve is examined. As the test procedure in obtaining the Soil–Water Characteristic curve is tedious and time-consuming, empirical relationships based on multivariate analysis relating the parameters of the Fredlund and Xing (1994) Soil–Water Characteristic curve equation to basic Soil properties are suggested for the Singapore residual Soils. The multivariate equations were found to be suitable for providing a quick preliminary estimate of the Soil–Water Characteristic curve of Singapore residual Soils.

  • Soil Water Characteristic curves of singapore residual Soils
    Geotechnical and Geological Engineering, 2001
    Co-Authors: S. S. Agus, E. C. Leong, H. Rahardjo
    Abstract:

    Soil–Water Characteristic curves were obtained for a number of Singapore residual Soil samples. Soil samples were obtained from the two main residual Soil formations, the Jurong sedimentary formation and the Bukit Timah granitic formation, at various depths. The effect of weathering on the shape of the Soil–Water Characteristic curve is examined. As the test procedure in obtaining the Soil–Water Characteristic curve is tedious and time-consuming, empirical relationships based on multivariate analysis relating the parameters of the Fredlund and Xing (1994) Soil–Water Characteristic curve equation to basic Soil properties are suggested for the Singapore residual Soils. The multivariate equations were found to be suitable for providing a quick preliminary estimate of the Soil–Water Characteristic curve of Singapore residual Soils.

D. G. Toll - One of the best experts on this subject based on the ideXlab platform.

  • Relationship between porosimetry measurement and Soil–Water Characteristic curve for an unsaturated residual Soil
    Geotechnical & Geological Engineering, 2001
    Co-Authors: K. K. Aung, H. Rahardjo, Ec Leong, D. G. Toll
    Abstract:

    Soil–Water Characteristic curve (SWCC) is an important tool for determining the engineering properties of unsaturated Soil. This depends on the size and distribution of pore structures which control the permeability and amount of volume change. Mercury Intrusion Porosimetry tests can be used to determine the size, amount and distribution of pore spaces of the Soil in a shorter time period compared to the pressure plate test. A Soil-air Characteristic curve (SACC) can be determined using the volumetric air content as measured in the Mercury Intrusion Porosimetry test. In this paper, SACC parameters are introduced. There appears to be a relationship between the Soil-air Characteristic curve and the Soil-Water Characteristic curve of a Soil. Relations between the SACC and the SWCC parameters are analysed in the light of unsaturated Soil mechanics. The results indicate that the pore size distribution of a residual Soil varies with depth due to differing degrees of weathering.

  • relationship between porosimetry measurement and Soil Water Characteristic curve for an unsaturated residual Soil
    Geotechnical and Geological Engineering, 2001
    Co-Authors: K. K. Aung, E. C. Leong, H. Rahardjo, D. G. Toll
    Abstract:

    Soil–Water Characteristic curve (SWCC) is an important tool for determining the engineering properties of unsaturated Soil. This depends on the size and distribution of pore structures which control the permeability and amount of volume change. Mercury Intrusion Porosimetry tests can be used to determine the size, amount and distribution of pore spaces of the Soil in a shorter time period compared to the pressure plate test. A Soil-air Characteristic curve (SACC) can be determined using the volumetric air content as measured in the Mercury Intrusion Porosimetry test. In this paper, SACC parameters are introduced. There appears to be a relationship between the Soil-air Characteristic curve and the Soil-Water Characteristic curve of a Soil. Relations between the SACC and the SWCC parameters are analysed in the light of unsaturated Soil mechanics. The results indicate that the pore size distribution of a residual Soil varies with depth due to differing degrees of weathering.