Field measurements of overlap reductions for two reinforced fabric-encased geosynthetic clay liners (GCLs)

Abstract

Abstract:Two GCLs reported to have experienced significant shrinkage at other locations are examined on both a 3H:1V south facing slope and a relatively flat base on a silty-sand. The GCLs were overlapped by 300 mm with 400 g/m of supplemental bentonite and covered by a black 1.5 mm HDPE geomembrane to form a composite liner which was left exposed in a full-scale field test embankment for a period of almost five years. It is shown that despite the relatively uniform exposure conditions, shrinkage is highly variable with a maximum shrinkage of GCL A being 165 mm on the slope and 415 mm on the base while GCL B shrunk by up to 75 mm on the side slope and only up to 25 mm on the base. The dominant role played by variable overlap stick and heterogeneity to the locations where the overlaps are re-wetted are discussed. Based on this study of shrinkage and a related study of down-slope erosion at the same site, it is concluded that neither GCLs A and B should not be left in exposed composite liners when they can be subjected to thermal cycles that can lead to hydration and dehydration of the GCL.

Performances of the Soil–Bentonite Cutoff Wall Composited with Geosynthetic Clay Liners: Large-Scale Model Tests and Numerical Simulations

“…Previous researchers and participants have identified the critical role of the GCL overlap in maintaining the effective contaminant [4,5] and investigated the effects of contributing factors, namely, confining stress and supplemental bentonite applied at the overlap, on hydraulic performances of the GCL overlap [6]. Granular and powder bentonite ranging from 400 to 600 g/m are two common materials of supplemental bentonite in the application of bottom liners and cover systems [7][8][9][10]. Both materials may be unsuitable for improving the permeation of the cutoff wall considering that they tend to move downward under gravity.…”

Effect of overburden confining stress on hydraulic performance of geosynthetic clay liners (GCLs)

“…The most significant challenge faced by the industry is the failure of the liner systems due to separation of panels on side slopes, separation of panels due to shrinkage, punctures and wrinkles, installation faults, liner design faults etc (Fox et al, 1998;Rowe, 2014;Rowe et al, 2017;Thiel et al, 2005). Hence, significant research is being carried out to investigate how the overall hydraulic performance of the GCL could be improved by maintaining its optimum capacity throughout the barrier application (Daniel et al, 1997;Egloffstein et al, 2012;Mazzieri et al, 2015;Rowe et al, 1997Rowe et al, , 2016Weerasinghe et al, 2020;Xiong et al, 2009).…”