Unsaturated Soil Mechanics

Speaker Title Summary Duration
Prof. Delwyn G. Fredlund Chapter 1 - Introduction to Unsaturated Soil Mechanics The first lecture introduces unsaturated soils by illustrated practical problems. The link between field and laboratory conditions is established by the “Soil-Water Characterization Curve” (SWCC) also called the soil retention curve. 41min Click to view
Prof. Delwyn G. Fredlund Chapter 2 - State Variables and their Measurement The second lecture presents the state variables by which the transition from the saturated soil condition to the unsaturated soil condition can be described, in particular the matric suction as the difference between pore-air and pore-water pressures. The measurement of soil suction helps in linking the state of stresses in field and laboratory conditions. 34min Click to view
Prof. Delwyn G. Fredlund Chapter 3 - The Soil-Water Characteristic Curve, SWCC The third lecture details the determination of SWCC in providing information about the amount of water and the energy state in water phase. The experimental measurement of the SWCC is explained and inherent parameters depending on the type of soil are introduced. 50min Click to view
Prof. Delwyn G. Fredlund Chapter 4 - Seepage through Unsaturated Soils The fourth lecture is dedicated to the theory and solution dealing with water flow problems in unsaturated soil. Focus is made on the measurement of unsaturated coefficient of permeability function for design purposes. Steady state and unsteady (transient) state methodologies are explained for the calculation of unsaturated coefficients of permeability. Selected water flow case studies are shown. 51min Click to view
Prof. Delwyn G. Fredlund Chapter 5 - Shear Strength of Unsaturated Soils Lecture five addresses the determination of shear strength of unsaturated soils. The latter is described by two independent state variables among which soil suction contributes to the cohesive component of soil. Measurement of shear strength of unsaturated soils is conducted by the conventional shear box and triaxial equipment needing modifications to allow air-entry in tested specimens. Using the shear strength parameters of unsaturated soil, current soil mechanics applications: e.g. earth pressures, bearing capacity and slope stability of foundations are formulated. 45min Click to view
Prof. Delwyn G. Fredlund Chapter 6 - Volume Change & Deformation of Unsaturated Soils In the sixth lecture, the theory with related solution of stress deformation problems is investigated. The main objective is to establish the relation between stress state variables and deformation strain state variables for unsaturated soils. In this process, the use of SWCC enables the assessment of the behaviour of unsaturated soil. 39min Click to view