The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Mingyi Zhang - One of the best experts on this subject based on the ideXlab platform.
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theory and application of a novel soil freezing Characteristic Curve
Applied Thermal Engineering, 2018Co-Authors: Ruiqiang Bai, Yuanming Lai, Mingyi ZhangAbstract:Abstract Unfrozen water in frozen soil is a key factor for water migration, frost heave and thaw settlement under freeze-thaw cycles. The relationship between unfrozen water content and temperature in frozen soil is known as soil freezing Characteristic Curve. The integral form for a soil freezing Characteristic Curve was derived from the perspective of soil pore structure in this study. According to the relationship between pore radius and freezing temperature, using existed test data, a distribution function was basically determined. Then, theoretical expression of the soil freezing Characteristic Curve was proposed. The calculated results by the theoretical expression were in good agreement with the test data. The parameters of the soil freezing Characteristic Curve have clear physical meanings, and the theoretical expression is continuous at the point of initial freezing temperature. In order to apply the proposed theoretical expression to coupled hydro-thermal-vapor transfer model, the equation was substituted into a coupled hydro-thermal-vapor transfer model, and the numerical simulations for frozen soils were carried out. The simulated results illustrated the reasonableness of the proposed equation.
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estimating soil freezing Characteristic Curve based on pore size distribution
Applied Thermal Engineering, 2017Co-Authors: Chong Wang, Yuanming Lai, Mingyi ZhangAbstract:Abstract A clear fundamental understanding of the soil freezing Characteristic Curve is crucial for studying soil freezing behavior. In this paper, based on the assumption that the shape of the soil freezing Characteristic Curve is mainly dependent upon the pore-size distribution of the soil, a mathematic model for estimating the soil freezing Characteristic Curve is proposed. The formula has the form of an integrated frequency distribution Curve, which is verified by previous researches (seven representative soil samples and six representative mineral compositions, a number of special mineral particles and soils, and unsaturated soils). By nonlinear Curve fitting, the correlation coefficients are generally larger than 0.95. The proposed model is more convenient than the original empirical formulas in numerical modeling, and it can overcome the shortcoming that the original empirical formulas are not derivative at the temperatures near the freezing point. In addition, the proposed model directly expresses the relationship between residual unfrozen water content and temperature under extremely low temperature conditions. Of course, the new model and results in this study may provide a reference for the research on basic physical properties of freezing soils, and the related numerical modeling in cold regions engineering.
Qian Zhai - One of the best experts on this subject based on the ideXlab platform.
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estimation of unsaturated shear strength from soil water Characteristic Curve
Acta Geotechnica, 2019Co-Authors: H. Rahardjo, Qian Zhai, Alfrendo SatyanagaAbstract:Many shallow foundations are constructed within the soil layer above the groundwater table, where the soil remains unsaturated, and the failure of shallow foundation is mostly related to shear failure. The shear strength of the unsaturated soil is one of the main engineering properties required in geotechnical designs. Previous researchers suggested that the shear strength of the unsaturated soil depends on matric suction in the soil. The shape of the soil–water Characteristic Curve (SWCC) has a significant effect on the Characteristics of unsaturated shear strength with respect to matric suction. In this paper, a new model was proposed for the estimation of the unsaturated shear strength from SWCC. In this new model, meniscus was considered to transfer soil suction into both additional net normal stress and additional cohesion. Based on the categorization from soil science, water in soil can be categorized into three groups: (1) gravity water, (2) capillary water and (3) hygroscopic water. The elemental analysis on the contractile skin indicated that only the capillary water in the soil can transfer stress into soil skeleton. Consequently, the SWCC is modified by considering capillary water only for the estimation of unsaturated shear strength. In the derivation, unsaturated soil is considered as four-phase material. Finally, a new mathematical equation for the estimation of the unsaturated shear strength was proposed and verified with the experimental data from the published literature. In addition, the proposed equation does not consist of any empirical parameter and can be used to predict the shear strength of unsaturated soil.
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estimation of the air permeability function from the soil water Characteristic Curve
Engineering Geology, 2015Co-Authors: Qian Zhai, H. Rahardjo, Alfrendo SatyanagaAbstract: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...
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quantification of uncertainties in soil water Characteristic Curve associated with fitting parameters
Engineering Geology, 2013Co-Authors: Qian Zhai, H. RahardjoAbstract:Abstract Soil–water Characteristic Curve (SWCC) is commonly expressed using best fit equations with several fitting parameters. These fitting parameters are determined by best fitting experimental data with the best fit equations. Residual errors always exist after the regression procedure for the determination of these fitting parameters. Statistical theory suggests that uncertainties of the determined SWCC can be estimated from the variance of these fitting parameters and the residual errors. In this paper, equations for the confidence limits of the best fitted SWCC are developed to quantify the uncertainties in the determined SWCC associated with the fitting parameters. Applications of the confidence limits in evaluating the performance of best fit equations and suggestion for experimental measurements are presented in this paper.
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determination of soil water Characteristic Curve variables
Computers and Geotechnics, 2012Co-Authors: Qian Zhai, H. RahardjoAbstract: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.
H. Rahardjo - One of the best experts on this subject based on the ideXlab platform.
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estimation of unsaturated shear strength from soil water Characteristic Curve
Acta Geotechnica, 2019Co-Authors: H. Rahardjo, Qian Zhai, Alfrendo SatyanagaAbstract:Many shallow foundations are constructed within the soil layer above the groundwater table, where the soil remains unsaturated, and the failure of shallow foundation is mostly related to shear failure. The shear strength of the unsaturated soil is one of the main engineering properties required in geotechnical designs. Previous researchers suggested that the shear strength of the unsaturated soil depends on matric suction in the soil. The shape of the soil–water Characteristic Curve (SWCC) has a significant effect on the Characteristics of unsaturated shear strength with respect to matric suction. In this paper, a new model was proposed for the estimation of the unsaturated shear strength from SWCC. In this new model, meniscus was considered to transfer soil suction into both additional net normal stress and additional cohesion. Based on the categorization from soil science, water in soil can be categorized into three groups: (1) gravity water, (2) capillary water and (3) hygroscopic water. The elemental analysis on the contractile skin indicated that only the capillary water in the soil can transfer stress into soil skeleton. Consequently, the SWCC is modified by considering capillary water only for the estimation of unsaturated shear strength. In the derivation, unsaturated soil is considered as four-phase material. Finally, a new mathematical equation for the estimation of the unsaturated shear strength was proposed and verified with the experimental data from the published literature. In addition, the proposed equation does not consist of any empirical parameter and can be used to predict the shear strength of unsaturated soil.
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estimation of the air permeability function from the soil water Characteristic Curve
Engineering Geology, 2015Co-Authors: Qian Zhai, H. Rahardjo, Alfrendo SatyanagaAbstract: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...
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effect of range of soil water Characteristic Curve measurements on estimation of permeability function
Engineering Geology, 2015Co-Authors: Arezoo Rahimi, H. Rahardjo, E. C. LeongAbstract: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.
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quantification of uncertainties in soil water Characteristic Curve associated with fitting parameters
Engineering Geology, 2013Co-Authors: Qian Zhai, H. RahardjoAbstract:Abstract Soil–water Characteristic Curve (SWCC) is commonly expressed using best fit equations with several fitting parameters. These fitting parameters are determined by best fitting experimental data with the best fit equations. Residual errors always exist after the regression procedure for the determination of these fitting parameters. Statistical theory suggests that uncertainties of the determined SWCC can be estimated from the variance of these fitting parameters and the residual errors. In this paper, equations for the confidence limits of the best fitted SWCC are developed to quantify the uncertainties in the determined SWCC associated with the fitting parameters. Applications of the confidence limits in evaluating the performance of best fit equations and suggestion for experimental measurements are presented in this paper.
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water Characteristic Curve of soil with bimodal grain size distribution
Computers and Geotechnics, 2013Co-Authors: Alfrendo Satyanaga, H. Rahardjo, Eng Choon Leong, Jingyuan WangAbstract:Abstract Soil–water Characteristic Curve (SWCC) is the most fundamental and important soil property in unsaturated soil mechanics. It has been used for analyzing slope stability due to the infiltration of rainfall into slopes and water flow in unsaturated embankments. Generally, SWCC is obtained by laboratory tests. However high cost, long duration and difficulty of the tests impede the application of unsaturated soil mechanics to practical design or analysis. Therefore, several equations have been developed to predict the SWCC using grain-size distribution (GSD) Curve. However, most of the equations were limited to soils with unimodal Characteristics and the parameters of the equations are not related to the physical properties of the soil. In this paper, an equation to predict SWCC for soils with bimodal Characteristics is proposed. The parameters of the proposed equation are related to the physical properties of soil and the variables of SWCC closely. The proposed equation is evaluated with data from the literature and laboratory tests carried out in this study. In addition, the computer codes for the computation of the predicted bimodal SWCC are presented.
Yuanming Lai - One of the best experts on this subject based on the ideXlab platform.
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theory and application of a novel soil freezing Characteristic Curve
Applied Thermal Engineering, 2018Co-Authors: Ruiqiang Bai, Yuanming Lai, Mingyi ZhangAbstract:Abstract Unfrozen water in frozen soil is a key factor for water migration, frost heave and thaw settlement under freeze-thaw cycles. The relationship between unfrozen water content and temperature in frozen soil is known as soil freezing Characteristic Curve. The integral form for a soil freezing Characteristic Curve was derived from the perspective of soil pore structure in this study. According to the relationship between pore radius and freezing temperature, using existed test data, a distribution function was basically determined. Then, theoretical expression of the soil freezing Characteristic Curve was proposed. The calculated results by the theoretical expression were in good agreement with the test data. The parameters of the soil freezing Characteristic Curve have clear physical meanings, and the theoretical expression is continuous at the point of initial freezing temperature. In order to apply the proposed theoretical expression to coupled hydro-thermal-vapor transfer model, the equation was substituted into a coupled hydro-thermal-vapor transfer model, and the numerical simulations for frozen soils were carried out. The simulated results illustrated the reasonableness of the proposed equation.
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estimating soil freezing Characteristic Curve based on pore size distribution
Applied Thermal Engineering, 2017Co-Authors: Chong Wang, Yuanming Lai, Mingyi ZhangAbstract:Abstract A clear fundamental understanding of the soil freezing Characteristic Curve is crucial for studying soil freezing behavior. In this paper, based on the assumption that the shape of the soil freezing Characteristic Curve is mainly dependent upon the pore-size distribution of the soil, a mathematic model for estimating the soil freezing Characteristic Curve is proposed. The formula has the form of an integrated frequency distribution Curve, which is verified by previous researches (seven representative soil samples and six representative mineral compositions, a number of special mineral particles and soils, and unsaturated soils). By nonlinear Curve fitting, the correlation coefficients are generally larger than 0.95. The proposed model is more convenient than the original empirical formulas in numerical modeling, and it can overcome the shortcoming that the original empirical formulas are not derivative at the temperatures near the freezing point. In addition, the proposed model directly expresses the relationship between residual unfrozen water content and temperature under extremely low temperature conditions. Of course, the new model and results in this study may provide a reference for the research on basic physical properties of freezing soils, and the related numerical modeling in cold regions engineering.
Alfrendo Satyanaga - One of the best experts on this subject based on the ideXlab platform.
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estimation of unsaturated shear strength from soil water Characteristic Curve
Acta Geotechnica, 2019Co-Authors: H. Rahardjo, Qian Zhai, Alfrendo SatyanagaAbstract:Many shallow foundations are constructed within the soil layer above the groundwater table, where the soil remains unsaturated, and the failure of shallow foundation is mostly related to shear failure. The shear strength of the unsaturated soil is one of the main engineering properties required in geotechnical designs. Previous researchers suggested that the shear strength of the unsaturated soil depends on matric suction in the soil. The shape of the soil–water Characteristic Curve (SWCC) has a significant effect on the Characteristics of unsaturated shear strength with respect to matric suction. In this paper, a new model was proposed for the estimation of the unsaturated shear strength from SWCC. In this new model, meniscus was considered to transfer soil suction into both additional net normal stress and additional cohesion. Based on the categorization from soil science, water in soil can be categorized into three groups: (1) gravity water, (2) capillary water and (3) hygroscopic water. The elemental analysis on the contractile skin indicated that only the capillary water in the soil can transfer stress into soil skeleton. Consequently, the SWCC is modified by considering capillary water only for the estimation of unsaturated shear strength. In the derivation, unsaturated soil is considered as four-phase material. Finally, a new mathematical equation for the estimation of the unsaturated shear strength was proposed and verified with the experimental data from the published literature. In addition, the proposed equation does not consist of any empirical parameter and can be used to predict the shear strength of unsaturated soil.
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estimation of the air permeability function from the soil water Characteristic Curve
Engineering Geology, 2015Co-Authors: Qian Zhai, H. Rahardjo, Alfrendo SatyanagaAbstract: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...
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water Characteristic Curve of soil with bimodal grain size distribution
Computers and Geotechnics, 2013Co-Authors: Alfrendo Satyanaga, H. Rahardjo, Eng Choon Leong, Jingyuan WangAbstract:Abstract Soil–water Characteristic Curve (SWCC) is the most fundamental and important soil property in unsaturated soil mechanics. It has been used for analyzing slope stability due to the infiltration of rainfall into slopes and water flow in unsaturated embankments. Generally, SWCC is obtained by laboratory tests. However high cost, long duration and difficulty of the tests impede the application of unsaturated soil mechanics to practical design or analysis. Therefore, several equations have been developed to predict the SWCC using grain-size distribution (GSD) Curve. However, most of the equations were limited to soils with unimodal Characteristics and the parameters of the equations are not related to the physical properties of the soil. In this paper, an equation to predict SWCC for soils with bimodal Characteristics is proposed. The parameters of the proposed equation are related to the physical properties of soil and the variables of SWCC closely. The proposed equation is evaluated with data from the literature and laboratory tests carried out in this study. In addition, the computer codes for the computation of the predicted bimodal SWCC are presented.