Unsaturated Soil Property Functions for High Volume Change Materials

Abstract

Unsaturated soil property functions are necessary for numerical modeling of geotechnical engineering problems including transient seepage or contaminant transport involving unsaturated soils such as tailings or mine wastes. The accuracy of the input of material properties significantly influences the correctness of the numerical modeling results. Therefore, it is important to use appropriate unsaturated soil property functions in the numerical modeling of geotechnical engineering problems. The existing soil property functions proposed in the literature by many researchers are based on an implicit assumption that the soil does not undergo volume change as soil suction changes. These estimation techniques may produce reasonable results for soils that do not undergo volume change as soil suction changes (e.g., sands and silts). However, they are not suitable for the estimation of the unsaturated soil property functions for soils that undergo significant volume change as soil suction changes (e.g., Regina clay and Oil Sands Tailings). Revisions to the conventional methodology are proposed to accommodate the need of estimating the unsaturated soil properties for soils that undergo volume change as soil suction changes. The research in this thesis is restricted to the study of hydraulic and volume-mass properties related to the water phrase. The primary objective of this thesis is to develop and verify a revised methodology for estimating the coefficient of permeability function and the water storage function for soils that undergo volume change as soil suction is increased during a drying process. The scope of this thesis is directed at a theoretical study and research program investigating the hydraulic and volume-mass properties of soils that will change volumes as soil suction changes (e.g., Oil Sands Tailings). Laboratory data sets collected from the literature on Regina clay and Oil Sands Tailings have been used to verify the proposed theory. An experimental program has been carried out on Bulyanhulu tailings and Devon silt. Data collected has been used for verifying the proposed theory. A complete set of experimental data for each soil sample includes measured data of the SWCCs, shrinkage curves and the relationship between the saturated permeability versus void ratio.