Osmotic Suction as a Valid Stress State Variable in Unsaturated Soil Mechanics

by D. J. Miller, Colorado State Univ, Fort Collins, United States,
J. D. Nelson, Colorado State Univ, Fort Collins, United States,

Document Type: Proceeding Paper

Part of: Unsaturated Soils


The hypothesis of the research being presented is that the osmotic suction of soil pore fluid is an independent, valid stress sate variable for unsaturated soils. A review of concepts from interfacial thermodynamics and micromechanical equilibrium in colloidal systems is presented to illustrate the fundamental difference between matric and osmotic stress state variables. Ongoing experimental work described in more detail in a previous paper is oriented towards defining the roles of matric, osmotic, and total suction in the stress state and volume change behavior of unsaturated soils (Miller and Nelson, 1992). Testing is being conducted in two phases to determine: (1) matric and total suction moisture characteristics at various salt concentrations, and (2) unsaturated consolidation behavior in response to independently controlled changes in matric and osmotic suction. Preliminary results of the first phase of testing are discussed.

Subject Headings: Soil suction | Soil stress | Unsaturated soils | Suction | Soil properties | Micromechanics | Equilibrium | Colloids

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