Evaluation of the Hydraulic Conductivity of Geosynthetic Clay Liners

Abstract

The hydraulic conductivity of geosynthetic clay liners (GCLs) is not fully understood and certain gaps in knowledge are still present, such as the effect of coupled mechanical and chemical processes. The current study aimed to develop a simplified mathematical model to predict the hydraulic conductivity of GCLs, particularly regarding the coupled effects of mechanical and chemical processes. Based on Darcy's Law and Poiseuille’s Law, the method combines diffuse double layer (DDL) theory and fractal theory. External factors such as confining pressure and the concentration of the permeating solution, and inherent properties such as exchangeable cations, ionic radius, montmorillonite surface fractal dimension, the distance between two montmorillonite layers (m) after swelling at the exchangeable cation i (i denotes the primary exchangeable cations, such as Na+, Ca2+, K+, and Mg2+ in bentonite), density, and coefficient of viscosity of interlayer water between two montmorillonite layers, were considered. The proposed theoretical model gave relatively accurate predictions. A practical estimate of GCL hydraulic conductivity was also derived. The predictions were compared with experimental results and good qualitative agreement was found. From the experimental results, the proposed prediction model has a maximum deviation of ~1:10–10:1, and the empirical model has a mean deviation of ~1:15–15:1.

Numerical Investigation of Confining Pressure Effects on Microscopic Structure and Hydraulic Conductivity of Geosynthetic Clay Liners

“…Following the same procedure, ten COMSOL models for GCL permeation under different confining pressures ranging from 50 kPa to 500 kPa were developed accordingly, as summarized in Table 2. Figure 4 presents the concept of initial porosity (n0), mobile porosity (nm), total porosity in the swelling process (n) and tortuosity of the main flow paths (τ), as discussed in the subsequent sections of the study [34]. Initial porosity is defined as the portion of pore water in the domain before swelling, as indicated by the light blue color in Figure 4a.…”

“…where n0 is the initial porosity, L0 is the initial length of the side of the simulated domain area (mm), and A0 is the initial total granule area (mm 2 ), which can be calculated as Figure 4 presents the concept of initial porosity (n 0 ), mobile porosity (n m ), total porosity in the swelling process (n) and tortuosity of the main flow paths (τ), as discussed in the subsequent sections of the study [34]. Initial porosity is defined as the portion of pore water in the domain before swelling, as indicated by the light blue color in Figure 4a.…”

Study on the Effect of Desiccation Cracks on the Hydraulic Conductivity of Geosynthetic Clay Liner

“…This research focuses on geosynthetic clay liners (GCLs) and also in what way they communicate and interrelate, as well as how interaction improves their ability. GCLs work like single liners (similar to potable ponds) and a composite liner (as in some covers) [5,6]. The bentonite provides the principal obstacle to fluid movement through a GCL [7,8].…”

“…A liner is exposed to temperature, as well as stresses/strains similar o part of a physical-environmental system as the scheme ages [6,[11][12][13]. Various researches symbolize the impact of effluents and cracks, which works on hydraulic conductivity of compressed clay liners [5,11,14,15], montmorillonite mixes [16,17], and GCLs [18,19] still directed over the last twenty years. The hydraulic behavior of acceptable soil particles is affected via the interface among opening solutions as well as minerals in general.…”