Comparison of Saturated Hydraulic Conductivity Estimated by Three Different Methods

Abstract

This study compares saturated hydraulic conductivities (K s ) of three sandy soils such as coarse, medium and fine sand. The K s was obtained using three different methods: empirical methods based on the grain size analysis, the relative effective porosity model (REPM), and breakthrough curve analyses based on tracer tests. Column drainage tests were performed to characterize the water retention properties of the samples, which are required in the REPM. Bench scale tracer tests with various conditions were conducted to obtain reasonable linear velocities of the samples using breakthrough curve analyses and then K s was estimated using Darcy's law. For the REPM, the differences of K s for the coarse and fine sand soils were less than one order of magnitude; however, the difference of K s values between the empirical methods and the breakthrough curve analyses was larger than one order of magnitude. The comparison results suggest that the REPM can be a reliable method for estimating K s for soil grains, and is cost effective due to its experimental simplicity.

Improved Packing Model for Functionally Graded Sand-Fines Mixtures—Incorporation of Fines Cohesive Packing Behavior

“…The aim in this discussion is to investigate how incorporating the notion of fines cohesive packing affects the prediction of permeability, K, for granular materials. Porosity, which can be significantly affected by cohesive packing as mentioned earlier, is a major factor that impacts K. The Kozeny-Carman formula is frequently used for estimating K for mixed soils and granular materials [2,4,8,33,35,[74][75][76], where K is expressed as a function of porosity according to the following Equation 8:…”

“…Many physical properties of granular materials such as permeability, shear strength, elastic modulus, thermal conductivity and electrical resistivity depend on the packing state (or porosity) of the materials [1][2][3][4][5][6][7][8]. Therefore, preparation of mixed soil specimens at a target porosity (or void ratio) or predicting the porosity of such mixtures can be of great significance for several applications in earth and environmental sciences [8][9][10], as well as civil engineering [11][12][13][14][15].…”

Experimental methods to determine the hydraulic conductivity

“…The correlation methods estimate the K-value using a preset relationship with a soil property which is easy to determine (e.g. texture) and have the major advantage of being simpler and quicker than direct determination of the hydraulic conductivity [2][3].…”

“…The density of the solid matrix ρs is given by the ratio of dry sand mass, ms and the volume of solid particles Vs (for five sand samples): (2) Bulk density represents the ratio between dry sand mass, ms and the total volume of sand sample Vt:…”

Automated Laboratory Infiltrometer to Estimate Saturated Hydraulic Conductivity Using an Arduino Microcontroller Board

“…Tracers are used in groundwater studies to determinate Ks and infiltration rates at large scales, surface water-groundwater exchanges, among others. Tracers such as coloured dye, artificial radioactive tracers [20], bromide (Br) or tritiated water (HTO) [21], potassium bromide (KBr) [22], disodium-fluorescein, sulforhodamine B or lithium [23] can be artificially injected into aquifers. However, artificial tracers represent potential environmental risks due to their high persistence in the porous medium and they require expensive equipment to measure it.…”