Lateral diversion of capillary barrier

• Main Author: Ang, Minxin
• Other Authors: Harianto Rahardjo
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering::Civil engineering::Geotechnical
• Online Access: http://hdl.handle.net/10356/61035
• Institution: Nanyang Technological University

The capillary barrier is a two-layer soil system which consists of a fine-grained layer overlying a coarse-grained layer that helps to control the percolation of water into landfills. Under unsaturated conditions, the difference in permeability of the two soils limits the flow of water downwards into the waste layer. When rainfall occurs, water will be accumulated in the fine-grained layer and later leaves the system by evapotranspiration and lateral diversion. Lateral diversion is a technique whereby, the capillary barrier is being inclined at an angle so that water, under the forces of gravity, can flow along the fine-coarse interface to the nearest drainage. In this study, the effect of the hydraulic properties of the two soils on the lateral diversion length was investigated. A parametric study was conducted on the Soil-Water Characteristic Curve (SWCC) fitting parameters and the saturated coefficient of permeability, k_s. Two types of analyses were carried out: the analytical method and the numerical modeling. The results of the two types of analyses confirm that higher values of “a”, “n” and k_s of the fine-grained layer will increase the permeability of the fine-grained layer and thus increase the diversion length. In addition, higher values “m” and “n” of the coarse-grained layer will keep the water-entry value of the coarse-grained layer as low as possible which leads to a higher diversion length.