A relation of hydraulic conductivity — void ratio for soils based on Kozeny-Carman equation

2016 ◽  
Vol 213 ◽  
pp. 89-97 ◽  
Author(s):  
Xingwei Ren ◽  
Yang Zhao ◽  
Qinglu Deng ◽  
Jianyu Kang ◽  
Dexian Li ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Void Ratio

Predicting the saturated hydraulic conductivity of sand and gravel using effective diameter and void ratio

2004 ◽  
Vol 41 (5) ◽  
pp. 787-795 ◽  
Author(s):  
Robert P Chapuis
Keyword(s):  
Hydraulic Conductivity ◽  
Void Ratio ◽  
Saturated Hydraulic Conductivity ◽  
Effective Diameter ◽  
Predictive Capacity ◽  
K Value ◽  
Maximum Value ◽  
New Equation ◽  
Silty Soils ◽  
Sand And Gravel

This paper assesses methods to predict the saturated hydraulic conductivity, k, of clean sand and gravel. Currently, in engineering, the most widely used predictive methods are those of Hazen and the Naval Facilities Engineering Command (NAVFAC). This paper shows how the Hazen equation, which is valid only for loose packing when the porosity, n, is close to its maximum value, can be extended to any value of n the soil can take when its maximum value of n is known. The resulting extended Hazen equation is compared with the single equation that summarizes the NAVFAC chart. The predictive capacity of the two equations is assessed using published laboratory data for homogenized sand and gravel specimens, with an effective diameter d10 between 0.13 and 1.98 mm and a void ratio e between 0.4 and 1.5. A new equation is proposed, based on a best fit equation in a graph of the logarithm of measured k versus the logarithm of d102e3/(1 + e). The distribution curves of the differences “log(measured k) – log(predicted k)” have mean values of –0.07, –0.21, and 0.00 for the extended Hazen, NAVFAC, and new equations, respectively, with standard deviations of 0.23, 0.36, and 0.10, respectively. Using the values of d10 and e, the new equation predicts a k value usually between 0.5 and 2.0 times the measured k value for the considered data. It is shown that the predictive capacity of this new equation may be extended to natural nonplastic silty soils, but not to crushed soils or plastic silty soils. The paper discusses several factors affecting the inaccuracy of predictions and laboratory test results.Key words: permeability, sand, prediction, porosity, gradation curve.

Hydraulic conductivity of bentonite-sand mixtures

2000 ◽  
Vol 37 (2) ◽  
pp. 406-413 ◽  
Author(s):  
P V Sivapullaiah ◽  
A Sridharan ◽  
V K Stalin
Keyword(s):  
Hydraulic Conductivity ◽  
Water Retention ◽  
Void Ratio ◽  
Clay Content ◽  
Liquid Limit ◽  
Natural Soils ◽  
Waste Containment ◽  
Clay Liner

The use of bentonite alone or amended with natural soils for construction of liners for water-retention and waste-containment facilities is very common. The importance of bentonite content in reducing the hydraulic conductivity of liners is well recognised. The study illustrates the role of the size of the coarser fraction in controlling the hydraulic conductivity of the clay liner. It has been shown that at low bentonite contents the hydraulic conductivity of the liner varies depending on the size of the coarser fraction apart from clay content. At a given clay content, the hydraulic conductivity increases with an increase in the size of the coarser fraction. But when the clay content is more than that which can be accommodated within the voids of the coarser fractions, the hydraulic conductivity is controlled primarily by clay content alone. Four different methods of predicting hydraulic conductivity of the liners are presented. Using two constants, related to the liquid limit, the hydraulic conductivity can be predicted at any void ratio.Key words: clays, hydraulic conductivity, liquid limit, liners, void ratio.

Physical characteristics of sands amended with fly ash

Soil Research ◽  
1983 ◽  
Vol 21 (2) ◽  
pp. 147 ◽  
Author(s):  
DJ Campbell ◽  
WE Fox ◽  
RL Aitken ◽  
LC Bell
Keyword(s):  
Fly Ash ◽  
Hydraulic Conductivity ◽  
Binary Mixtures ◽  
Void Ratio ◽  
Coarse Sand ◽  
Power Station ◽  
Sand Fraction ◽  
Water Capacity ◽  
Available Water ◽  
Available Water Capacity

Fly ash from a coal-fired power station was incorporated with each of a 'fine' (0.2-0.5 mm) and 'coarse' (1.4-2.0 mm) sand fraction to give mixtures containing 0, 10, 20, 30, 40, 50, 75 and 100% fly ash by weight. The addition of 10% by weight of ash increased the available water capacity by factors of 7.2 (1.0-7.2% by weight) and 13.5 (0.4-5.4% by weight) for the 'fine' and 'coarse' sands respectively. Subsequent additional 10% increments of ash increased the capacity by smaller amounts. The saturated hydraulic conductivity of the sands decreased markedly with ash addition. The changes in available water capacity and hydraulic conductivity were associated with an increase in capillary pores at the expense of non-capillary pores. Addition of fly ash to both sand fractions resulted in a bilinear relationship between void ratio (volume voids/volume solids) and fly ash percentage in the mixes which was closely related to that theoretically predicted for binary mixtures. The measured void ratios of the mixes exhibited minimum values at 36% and 20% ash by volume for the 'fine' and 'coarse' sand mixes respectively, which compared with the theoretical void ratios for these mixes of 27% and 23% respectively.

scholarly journals One-dimensional large-strain thaw consolidation using nonlinear effective stress – void ratio – hydraulic conductivity relationships

2018 ◽  
Vol 55 (3) ◽  
pp. 414-426 ◽  
Author(s):  
Simon Dumais ◽  
Jean-Marie Konrad
Keyword(s):  
Heat Transfer ◽  
Hydraulic Conductivity ◽  
Effective Stress ◽  
Void Ratio ◽  
Moving Boundary ◽  
Initial Conditions ◽  
Large Strain ◽  
One Dimensional ◽  
Consolidation Theory ◽  
Thaw Consolidation

A one-dimensional model for the consolidation of thawing soils is formulated in terms of large-strain consolidation and heat-transfer equations. The model integrates heat transfer due to conduction, phase change, and advection. The hydromechanical behaviour is modelled by large-strain consolidation theory. The equations are coupled in a moving boundary scheme developed in Lagrangian coordinates. Finite strains are allowed and nonlinear effective stress – void ratio – hydraulic conductivity relationships are proposed to characterize the thawing soil properties. Initial conditions and boundary conditions are presented with special consideration for the moving boundary condition at the thaw front developed in terms of large-strain consolidation. The proposed model is applied and compared with small-strain thaw consolidation theory in a theoretical working example of a thawing fine-grained soil sample. The modelling results are presented in terms of temperature, thaw penetration, settlements, void ratio, and excess pore-water pressures.

scholarly journals Impact of In Situ Soil in Soil-Bentonite Cutoff Wall Backfill on Compressibility and Hydraulic Conductivity

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Ridong Fan ◽  
Yuling Yang ◽  
Songyu Liu
Keyword(s):  
Hydraulic Conductivity ◽  
Void Ratio ◽  
Size Fraction ◽  
Characteristic Parameter ◽  
Compression Index ◽  
Natural Clay ◽  
Cutoff Wall ◽  
Clay Size Fraction ◽  
The Impact

Soil-bentonite cutoff walls, consisting of excavated in situ soil and bentonite as backfills, are used extensively as vertical barriers for groundwater pollution control. Sand mixed with high-quality natural sodium bentonite (NaB) is commonly used as a research object to investigate the hydraulic and compression properties of soil-bentonite backfills. However, pure sand could rarely be found in real conditions, and natural NaB may not be available readily in some countries such as China, India, and Turkey. This paper presents a comprehensive laboratory investigation on the compressibility and hydraulic conductivity (k) of soil-bentonite backfills created by simulated in situ soil and low-quality sodium activated calcium bentonite (SACaB). The simulated in situ soils are prepared using sand-natural clay mixtures with sand to natural clay mass ratios ranging from 0.5 to 6.0, and the bentonite content (BC) in the base mixture ranges from 0 to 15%. The result indicates that BC dominates the compression index (Cc) of the backfill, and a unique relationship between void ratio at effective vertical compression stress of 1 kPa and compression index is proposed for various types of soil-bentonite backfills. An increase in either BC or clay size fraction (CF) in simulated in situ contributes to reducing k, but the impact of CF in simulated in situ soil on k tends to be insignificant for backfill with BC higher than 6%. A new characteristic parameter based on the concept of void ratio of bentonite (eb), named apparent void ratio of clay size fraction (eC), is developed for predicting soil-bentonite backfills created by in situ soils and bentonites with various contents.

scholarly journals Method to Determine the Constitutive Permeability Parameters of Non-Linear Consolidation Models by Means of the Oedometer Test

Mathematics ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 2237
Author(s):  
Gonzalo García-Ros ◽  
Iván Alhama
Keyword(s):  
Inverse Problem ◽  
Hydraulic Conductivity ◽  
Void Ratio ◽  
Linear Models ◽  
Constitutive Relations ◽  
Laboratory Data ◽  
Permeability Index ◽  
Oedometer Test ◽  
Non Linear ◽  
Constitutive Parameters

This paper presents an easy-to-apply methodology that allows obtaining the permeability index and the initial hydraulic conductivity of clayey soils, basic constitutive parameters in non-linear models of consolidation, based on the laboratory oedometer test. For this, the data of the void ratio, compressibility index and characteristic consolidation time are taken from the test and, as an inverse problem, the constitutive permeability parameters sought are determined by applying the universal solutions of the characteristic time for a general non-linear consolidation model with constitutive relations void ratio-effective soil stress and hydraulic conductivity-void ratio of logarithmic type. The application protocol of the inverse problem is described in detail and illustrated by a series of applications carried out on real laboratory data belonging to two different soils. The influence that errors in laboratory parameter measurements can have on the final values of the permeability index and initial hydraulic conductivity is studied, showing the maximum deviations that may appear and, by last, the precision of the results obtained.

scholarly journals Correction Method for Hydraulic Conductivity Measurements Made Using a Fixed Wall Permeameter

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Qiang Luo ◽  
Mengshi Liu ◽  
Tengfei Wang ◽  
Peng Wu
Keyword(s):  
Hydraulic Conductivity ◽  
Void Ratio ◽  
Geometric Model ◽  
Conductivity Measurement ◽  
Rigid Wall ◽  
Correction Method ◽  
Coarse Grained ◽  
Soil Matrix ◽  
Boundary Flow ◽  
Wall Cell

Hydraulic conductivity measurement through a fixed wall permeameter is a common practice to obtain the fluid transmissibility characteristics of soil matrix; however, sidewall leakage due to rigid wall effect may significantly influence the observed values for coarse-grained soils. In this study, the boundary flow error was identified through characterizing the geometrical properties of voids adjacent to the sidewall, and a parameter known as the boundary void ratio (eb) was proposed to account for this effect. The findings suggest that a fixed wall cell containing coarse soils would unavoidably generate extra voids at the interface between soil grains and inner rigid wall, contributing to a larger eb at the wall than void ratio within the soil bed; the measured hydraulic conductivity is increased primarily due to the apparatus-induced error. A two-dimensional geometric model was then established to estimate the eb value for uniformly sized coarse soils confined by a rigid permeameter wall, based on which a method was obtained for eliminating the boundary flow error from a fixed wall cell. The mathematical method was finally validated against experimental data from existing literature. It can be concluded that the boundary condition at sidewall featuring unwanted gaps lead to overestimation of the coefficient of permeability; however, the proposed correction method could adequately eliminate the boundary flow error for uniformly sized coarse-grained soils tested within a rigid wall cell.

scholarly journals The Modelling of Freezing Process in Saturated Soil Based on the Thermal-Hydro-Mechanical Multi-Physics Field Coupling Theory

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2684
Author(s):  
Dawei Lei ◽  
Yugui Yang ◽  
Chengzheng Cai ◽  
Yong Chen ◽  
Songhe Wang
Keyword(s):  
Thermal Conductivity ◽  
Hydraulic Conductivity ◽  
Void Ratio ◽  
Soil Column ◽  
Soil Freezing ◽  
Frost Heave ◽  
Freezing Process ◽  
Soil Particles ◽  
Initial Void Ratio ◽  
Freezing Depth

The freezing process of saturated soil is studied under the condition of water replenishment. The process of soil freezing was simulated based on the theory of the energy and mass conservation equations and the equation of mechanical equilibrium. The accuracy of the model was verified by comparison with the experimental results of soil freezing. One-side freezing of a saturated 10-cm-high soil column in an open system with different parameters was simulated, and the effects of the initial void ratio, hydraulic conductivity, and thermal conductivity of soil particles on soil frost heave, freezing depth, and ice lenses distribution during soil freezing were explored. During the freezing process, water migrates from the warm end to the frozen fringe under the actions of the temperature gradient and pore pressure. During the initial period of freezing, the frozen front quickly moves downward, the freezing depth is about 5 cm after freezing for 30 h, and the final freezing depth remains about 6 cm. The freezing depth of the soil column is affected by soil porosity and thermal conductivity, but the final freezing depth mainly depends on the temperatures of the top and lower surfaces. The frost heave is mainly related to the amount of water migration. The relationship between the amount of frost heave and the hydraulic conductivity is positively correlated, and the thickness of the stable ice lens is greatly affected by the hydraulic conductivity. With the increase of the hydraulic conductivity and initial void ratio, the formation of ice lenses in the soil become easier. With the increase of the initial void ratio and thermal conductivity of soil particles, the frost heave of the soil column also increases. With high-thermal-conductivity soil, the formation of ice lenses become difficult.

Hydraulic conductivity of natural clays permeated with simple liquid hydrocarbons

1985 ◽  
Vol 22 (2) ◽  
pp. 205-214 ◽  
Author(s):  
Federico Fernandez ◽  
Robert M. Quigley
Keyword(s):  
Dielectric Constant ◽  
Hydraulic Conductivity ◽  
Pore Water ◽  
Void Ratio ◽  
Pore Space ◽  
Water Soluble ◽  
Low Dielectric Constant ◽  
Simple Liquid ◽  
Liquid Hydrocarbons ◽  
Low Dielectric

The hydraulic conductivity, k, of clayey soils is strongly influenced by the physicochemical properties of permeating liquid hydrocarbons. Tests on natural Sarnia soils mixed with pure liquids at a void ratio of 0.8 yielded k values that increased from 5 × 10−9 to 1 × 10−4 cm/s as the dielectric constant of the permeant decreased from 80 to 2.Sequential permeation of compacted, water-wet samples (k ≈ 10−8 cm/s) showed no changes in hydraulic conductivity when permeated with water-insoluble hydrocarbons of low dielectric constant (benzene, cyclohexane, xylene). These hydrophobic liquids were forced through microchannels or macropores and displaced less than 10% of the pore water from samples at a void ratio of unity.Permeation with water-soluble alcohols resulted in extensive removal of the pore water and up to 10-fold increases in k. Subsequent permeation with liquid aromatics of very low dielectric constant resulted in 1000-fold increases in k with only 30% of the pore space occupied by the aromatics. Association liquids such as alcohol that are mutually soluble in water and the aromatics seem to be required to initiate huge increases in k over testing periods of short duration. Key words: hydraulic conductivity, liquid hydrocarbons, clay barriers, dielectric constant.

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