Numerical study of advective flow through composite liners

International audienceThis study presents numerical simulations of advective flow through a composite geomembrane geosynthetic clay liner(GMB-GCL). In the past, GCLs were considered homogeneous materials, but they actually consist of a special layeredcomposite structure that combines two types of materials, geotextiles and bentonite, which are connected togetherby various processes. One could imagine that, when the GCL hydrates, the different water-retention properties of thegeotextile and the bentonite affect the hydraulic behaviour of engineered systems, including GMB-GCL compositeliners. To investigate this question, the advective flow through a composite liner modelled as a GCL and a damagedGMB was numerically simulated to evaluate how the hydraulic properties of the unsaturated geotextile and bentoniteinfluences the temporal evolution of advective flow through composite liners. Results are compared with measuredwater-retention curves of geotextiles and bentonite. The simulation indicates that the reproduced flow rate is influencedby the desaturation of the geotextile that occurs as the bentonite hydrates. The reduction in flow rate is thus governedby the hydraulic conductivities of the geotextile and the bentonite, both of which vary with degree of saturation