Physical Model Test of Leakage through Composite Cut-Off Wall with Defective Geomembrane
Physical Model Test of Leakage through Composite Cut-Off Wall with Defective Geomembrane
The vertical composite geomembrane-cement bentonite (CGCB) cut-off wall, which consists of a layer of geomembrane sheet installed within cement-bentonite wall, has been widely used in pollution control and the remediation of contaminated sites as an effective barrier system. Compared to cut-off materials such as bentonite or cement-bentonite (CB), which are often sensitive to environmental changes, geomembrane can maintain good stability and very low permeability even under severe environmental conditions. However, because of construction activities and advised ground conditions, defects on geomembrane may occur during construction or over the long term. Once defects, such as holes or cracks, appear, the leakage flow rate through the geomembrane barrier system can increase substantially. Hence, this study explores the use of geomembrane coupled with CB in the cut-off wall. While various analytical models have been proposed to estimate leakage through CGCB cut-off wall, very limited of them have been validated through physical modelling. This study develops a novel laboratory apparatus to physically measure the leakage behaviour of a CGCB cut-off wall with defects on the geomembrane. A preliminary test conducted after about 5 days of CGCB cut-off wall curing yielded a system permeability of 2 × 107 m/s, which was much higher than the permeability measured from the 14-day cured CB specimens alone. This indicates that, at the early stage of CGCB cut-off wall, the presence of a geomembrane defect may lead to a higher system permeability than expected. Though the underlying mechanisms require further investigation, the proposed laboratory apparatus is validated to be useful for such study.
Zhiyong Jiang; Soon Hoe Chew; Kai En Low; Chuanjin Tang; Jun Yuan Lee; Tse Shing Seah
11th International Conference on Physical Modelling in Geotechnics (ICPMG2026)
Session 1: New facilities, new equipment, and measuring techniques
https://doi.org/10.53243/ICPMG2026-165