Estimation of permeability function from the soil–water characteristic curve

Zhai, Qian; Rahardjo, Harianto

doi:10.1016/j.enggeo.2015.11.001

Cited by 128 publications

(45 citation statements)

References 22 publications

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“…representing probability of random pore connections [57], since the region within the pore-suction distribution function defines the degree of saturation. An important parameter of the SWCC for unsaturated soil mechanics is the air-entry value (AEV), associated with matric suction where water starts to be drained out from the biggest soil pores [5].…”

Section: Unsaturated Soil Mechanicsmentioning

confidence: 99%

Role of unsaturated soil mechanics in geotechnical engineering

2019

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Significant changes in climatic conditions in past decades are affected mostly by the increase in global temperature. Many countries experienced longer days of rainfall with higher intensities. Despite numerous debates about the existence of global warming, over 97% of climatologists reached an agreement that the changes in global climatic conditions are affected mainly by human activities [9]. A study on one aspect of climate change by Kim et al. [24], Rahardjo et al. [46] and Strauch et al. [51] indicated that climate change resulted in higher rainfall intensity with lesser frequency of rainy days. In addition, more water vapour is retained in the atmosphere due to the increase in average air temperature, which causes an exponential increase in the water vapour carrying capacity of the air [37]. Significant amount of rainfalls attributed to the changes in global climatic conditions may result in more frequent of rainfall-induced slope failures which affect properties and human lives as studied by Ciabatta et al. [8]. Rahardjo et al. [45] carried out research works on residual soil slopes. They observed that high and steep residual soil slopes can stand safely during dry periods. These slopes only failed during rainy periods. This fact is associated with the presence of an additional shear strength within the unsaturated zone [13] above the groundwater table.in residual soil slope. Hence, the slope is stable with a high factor of safety during dry periods (Fig. 1). However, the infiltration of rainwater during rainfall affects the negative pore-water pressure, resulting in a decrease in the additional shear strength within the unsaturated zone. As a result, the slope is more

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Section: Unsaturated Soil Mechanicsmentioning

confidence: 99%

Role of unsaturated soil mechanics in geotechnical engineering

2019

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“…Consequently, the relative coefficient of permeability was calculated from a ratio between the equivalent cross sectional area of water flow in unsaturated state to the equivalent cross sectional area in saturated state. Childs and Collis-George (1950)'s model was further extended by Marshall (1958) and Kunze et al (1968), Mualem (1976), , Zhai and Rahardjo (2015), and Zhai et al (2017). Zhai and Rahardjo (2015) pointed out that only SWCC in the form of degree of saturation was analogous to the pore-size distribution function.…”

Section: R a F Tmentioning

confidence: 99%

“…Childs and Collis-George (1950)'s model was further extended by Marshall (1958) and Kunze et al (1968), Mualem (1976), , Zhai and Rahardjo (2015), and Zhai et al (2017). Zhai and Rahardjo (2015) pointed out that only SWCC in the form of degree of saturation was analogous to the pore-size distribution function. Zhai and Rahardjo (2015) also recommended that the permeability function to be estimated from the SWCC in the form of degree of saturation.…”

Section: R a F Tmentioning

confidence: 99%

Estimation of air permeability function from soil-water characteristic curve

2019

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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 the pore-size distribution function. Many models have been proposed to estimate the water flow or water permeability function, kw, from the 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 the 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 the pore-size distribution function. In the method proposed in this paper, no empirical parameters were adopted, and the estimation results purely depended on the soil-water characteristic curve. The proposed method was verified against experimental data from published literature.

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“…As a consequence, it is necessary to observe on-line UPC in the SWIS. UPC is the function of the degree of saturation, volumetric water content and matrix suction [7]. It can be measured directly in the laboratory or in the field [5].…”

Section: Introductionmentioning

confidence: 99%

The relationship between the unsaturated permeability coefficients (UPC) determined and oxidation-reduction potential (ORP) in the subsurface wastewater infiltration system (SWIS)

Li¹,

Zhang²,

Li³

et al. 2019

Desalination and Water Treatment

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a b s t r a c tThe estimation of unsaturated permeability coefficients (UPC) is of great importance on the properties of the matrix. Aim to study the relationship between the UPC and oxidation -reduction potential (ORP) in different matrix depths in the subsurface wastewater infiltration system (SWIS) and provide scientific basis for regulating SWIS and increasing pollutant removal, a test experiment of simulating the SWIS which included an inflow period (12 h) and a drying period (12 h) in one cycle was designed with a hydraulic load of 0.10 m 3 ·(m 2 ·d) -1 . Results investigated that ORP could increase with UPC increasing in 70 and 115 cm and decrease with the UPC increasing in 100 and 130 cm matrix depths. Phenomena indicated that capillary action could affect UPC and ORP obviously. Moreover, the existence of oxygen and low volumetric water contents could impose UPC and ORP. UPC in the 100 cm matrix depth below proved that anaerobic area could be found in aerobic environment under alternation conditions. UPC in different matrix depths of a satisfactory SWIS could change from 2.49 × 10 -7 to 1.16 × 10 -3 cm·s -1 . Treated water met reused requirements and no clogging was found.

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Estimation of permeability function from the soil–water characteristic curve

Cited by 128 publications

References 22 publications

Role of unsaturated soil mechanics in geotechnical engineering

Role of unsaturated soil mechanics in geotechnical engineering

Estimation of air permeability function from soil-water characteristic curve

The relationship between the unsaturated permeability coefficients (UPC) determined and oxidation-reduction potential (ORP) in the subsurface wastewater infiltration system (SWIS)

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