Probabilistic modelling of saturated/unsaturated hydraulic conductivity for compacted glacial tills

Abstract

A probabilistic model including some previous probabilistic studies is proposed to evaluate hydraulic conductivity from pore entrance size distribution. The model considers multi-pores in series of paths through capillary networks in the soil fabric. The average number of connected pores is a representative value of the fabric, greater than two but not too large. The hydraulic conductivity of three glacial tills from northern Québec with different grain-size distributions has been examined by horizontal permeability tests in saturated conditions, and suction tests with vertical permeability measurement in unsaturated conditions. The hydraulic conductivity is strongly influenced by compaction conditions corresponding to different microfabrics. The model is applicable not only in saturated conditions but also in unsaturated conditions with different microfabrics.

Hydraulic conductivity and compressibility of mixtures of Nagoya clay with sand or bentonite

“…Recently, the general capillary model (Watabe et al, 2006), which comprehensively includes the above two models, has been proposed. In this section the hydraulic conductivity of sand/ bentonite-clay mixtures is evaluated using the general capillary model.…”

“…The value of N p in the summation equations (equations (3) and (5)) must be a natural number; however, it is not necessarily a natural number in the integral equation derived in Watabe et al (2006).…”

“…Watabe et al (2006) proposed the general capillary model, which is a probabilistic model that comprehensively includes previous probability models such as the capillary model (Garcia-Bengochea et al, 1979) and Marshall's model (Childs & Collis-George, 1950;Marshall, 1958) to evaluate hydraulic conductivity using the pore entrance size distribution. The pore entrance size distribution can be obtained by intrusion of mercury into a dry specimen with a fine fabric (i.e.…”

“…mercury intrusion porosimetry; Garcia-Bengochea et al, 1979;Lapierre et al, 1990), or by the intrusion of air into an initially saturated specimen with coarse fabric (i.e. the suction test; Marshall, 1958;Watabe et al, 2000Watabe et al, , 2006.…”

“…In this study the hydraulic conductivity of sand/ bentonite-clay mixtures is discussed using the general capillary model. This probabilistic approach is similar to those used to study reconstituted clay (Lapierre et al, 1990), silt and clay mixtures (Garcia-Bengochea et al, 1979) and glacial tills (Watabe et al, 2000(Watabe et al, , 2006.…”