Seepage through a Circular Geomembrane Hole when covered by Fine-Grained Tailings under Filter Incompatible Conditions

Abstract

Experiments are conducted to quantify leakage through a circular geomembrane (GMB) hole using two types of underliner not meeting modern filter criteria. Test results show that a 1.9 and 5.0-fold increase in hole diameter cause a 1.8 and 6.2-fold increase in leakage, respectively; while a 2-fold increase in GMB thickness results in an approximate 10% decrease in leakage. For a constant effective stress, a 2 and 3-fold increase in water head above the GMB lead to a 1.8 and 2.5-fold increase in leakage, respectively. The effect of the intrusion of underliner materials through the hole is quantified. A numerical model, considering the localized concentration of head loss around the hole and the consequent non-homogeneity in hydraulic conductivity due to the seepage force, is presented. It is shown that percent of head loss within the hole and from the hole to any position above the GMB are independent of loading conditions, and are only influenced by the GMB thickness and hole diameter. Finally, empirical equations for predicting leakage through a circular GMB hole in tailings storage applications are proposed.