The Effective Stress Equation
Pp. 12-23 (12)
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.