摘要：The saturated hydraulic conductivity of a coarse-grained material is normally higher than that of a fine-grained material. However, the unsaturated hydraulic conductivity of the coarse-grained material decreases much faster than that of the fine-grained material with increasing matric suction and consequently the coarse-grained material can be less permeable than the fine-grained material in unsaturated condition. A capillary barrier system with a fine-grained layer over a coarse-grained layer will act as a hydraulic barrier to minimize rainwater infiltration into the original soil. Geobarrier system (GBS) which can function as both a cover system (i.e. prevention of rainwater infiltration) and a retaining structure was designed and will be constructed at Orchard Boulevard in Singapore. Numerical simulations were carried out to determine the optimallocations of instruments that can be used to assess the performance of GBS during dry and wet periods. The monitoring results from tensiometers, earth pressure cells and weather station would be used to validate the results from the numerical analyses
