A pore-size distribution function based method for estimation of hydraulic properties of sandy soils

Abstract

Hydraulic property of soil is key information required for understanding the groundwater flow in the soil (including saturated and unsaturated zone). The water flow in soil is governed by the geometrical pore-space characteristics of soil structure (i.e., pore-size distribution function). Even though the concept of pore-size distribution function had been proposed decades ago, the pore-size distribution function is rarely used to estimate the hydraulic properties in engineering practice. In practice, the effective particle size (i.e., d10) and void ratio (e) are commonly used for the estimation of saturated coefficient of permeability, ks, for sandy soils. Neither d10 nor e can accurately represent the geometrical pore space in soil. With the development of unsaturated soil mechanics, it is observed that the pore-size distribution function can be expressed in another form which is named as soil-water characteristic curve (SWCC). In this study, the coefficients of permeability of sandy soils were estimated using the concept of “pore-size distribution function” (or SWCC). The comparison between the estimated results using the proposed equation and the measured data from laboratory tests in Nanyang Technological University (NTU) showed that the proposed equation in this note provided good estimation of ks.