Towards a Unified Soil Mechanics Theory: The Use of Effective Stresses in Unsaturated Soils

Indexed in: EBSCO, Book Citation Index, Science Edition.

With the application of the effective stress concept, the strength and volumetric behavior of saturated materials was clearly understood. For the case of unsaturated materials, a universally accepted ...
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The Effective Stress Equation

Pp. 12-23 (12)

DOI: 10.2174/9781608057399113010006

Author(s): Eduardo Rojas


Based on the analysis of the equilibrium of solid particles of an unsaturated sample subject to certain suction it is possible to establish an analytical expression for Bishop´s parameter X. The resulting stress can be used to predict the shear strength and volumetric behavior of unsaturated soils. This equation clarifies some features of the strength of unsaturated soils that up to now had no apparent explanation. The effective stress parameter X is written as a function of three quantities: the saturated fraction, the unsaturated fraction and the degree of saturation of the unsaturated fraction of the sample. A drawback to this expression is that the determination of these three parameters cannot be made from current experimental procedures.


Equilibrium, total stress, effective stress, suction, volumetric behavior, shear strength, effective stress parameter, saturated fraction, unsaturated fraction, dry fraction, degree of saturation of the unsaturated fraction, microstructure, macrostructure, water menisci, homogeneous material.