A Method to Improve the Performance of Capillary Barriers Using Heated Air Flow

• Main Author: Salah, Mohammad
• Other Authors: Infante, Jules-Ange
• Format: Others
• Language: en
• Published: Université d'Ottawa / University of Ottawa 2020
• Subjects: Capillary Barriers; Thermodynamic Behaviour of Unsaturated Soil
• Online Access: http://hdl.handle.net/10393/41100; http://dx.doi.org/10.20381/ruor-25324

The investigation described in this thesis is aimed at determining the effect of heated air flow on the behaviour of capillary barriers. In order to achieve the objectives of this investigation, a number of tasks were undertaken, as described hereinafter. First, a laboratory scale testing was carried out to determine the effect of heated air flow on the volumetric water content (VWC) and matric suction in a layer of soil representing the coarse grained soil layer of a capillary barrier. Several types of instruments were used to measure the VWC, matric suction, and temperature at different locations within the soil. Next, a numerical analysis was undertaken to simulate the behaviour of the soil mass subjected to thermal changes in the laboratory experiments. Lastly, two case studies were analyzed with and without the heated air flow in the coarse grained soil layer to validate the proposed model. The method used in this investigation was based on: (1) application of temperature change at the perimeters of the pipes installed in the coarse grained soil layer near the interface between the fine grained and coarse grained soil layers; and, (2) application of suction as a boundary condition at the perforated parts of the pipes to decrease VWC and increase matric suction in the soil mass. Using this specific method, the results of the finite element analyses of the laboratory experiments and the two case studies demonstrated that the heated air flow through the coarse grained soil layer of a capillary barrier would improve its performance as a soil cover for a number of engineering applications. Comparisons of measured and calculated values of VWC and matric suction showed good agreement providing further proof of the validity of the method.