Prediction of geosynthetic clay liner desiccation in low stress applications

Abstract

The risk of geosynthetic clay liner (GCL) desiccation in low stress applications such as solar ponds was investigated using a fully coupled thermo-hydro-mechanical model. Parameters were developed and verified by comparison with previously reported laboratory data. A parametric study was performed to establish recommendations for future investigation. The water retention curve of the GCL was found to have a significant effect on the conditions that are expected to cause desiccation. The temperature coefficient of the water retention curve was also found to have a significant effect, yet this parameter is not well defined. Poisson's ratio was found to affect the risk of desiccation in proportion to the applied stress. As reported by previous researchers, the initial degree of saturation of a GCL was found to influence desiccation; however, the effect was diminished at low applied stress. The magnitude of the increase in liner temperature, above groundwater temperature, was found to have the potential to cause desiccation of a GCL in a composite liner.

Hydraulic Flow through Engineering Bentonite-Based Containment Barriers

“…The bentonite in the linear system generally is found either as air dried granulated/powdered or as prehydrated and extruded form. The loss of its function as a barrier in dry system due to desiccation cracking are incessantly reported by numerous people (He et al, 2015;Rowe and Verge, 2013;Wijeyesekera et al, 2012;Scalia and Benson, 2011;Egloffstein, 2001;Hewitt and Philip, 1999). A non-uniform distribution of granulated bentonite accentuates the formation of crack patterns.…”

State-of-the-art report: GCL shear strength and its measurement – ten-year update

“…Although experimental and numerical studies have focused on thermo-hydro-mechanical behavior and potential for desiccation at elevated temperatures (e.g. Boardman and Daniel 1996;Rowe 2005a, 2005b;Azad et al 2011Azad et al , 2012Rowe and Verge 2013), little information has been published on corresponding effects for shear strengths of GCLs and GCL interfaces. 7.…”

Insights into Desiccation and Self-Healing of Bentonite in Geosynthetic Clay Liners under Thermal Loads

“…In several engineering applications, GCLs are exposed to significant thermal gradients can cause dehydration and desiccation of the bentonite, with consequent loss of performance [1][2][3][4][5][6][7][8][9][10]. These applications include heat-generating organic waste in municipal waste landfills, incineration ash and other industrial waste in hazardous-waste landfills, solar ponds and brine ponds, especially on coal-seam gas extraction sites.…”

“…Past research on GCLs under thermal loads has led to important insights into their behaviour in single [1,2] and double [3,4] composite liner systems in waste landfills where moderate thermal gradients and high overburden loads (>200 kPa) occur. More recently, behaviour under higher thermal gradients and lower loads has been studied numerically [5,6] and experimentally [7][8][9][10]. However, significant uncertainties remain about the ability of multi-phase theories of behaviour, including critical-state soil mechanics, to predict bentonite dehydration, desiccation and self-healing under these conditions.…”