Equivalent Stress Equation for Unsaturated Soils. II: Solid-Porous Model

Review of fundamental principles in modelling unsaturated soil behaviour

“…Most of these equations are empirically based and are defined independently from the volume change equation, which, if incorporated into a constitutive model, may lead to inconsistency with the yield surface as discussed in the Section above. Rojas [94,95] presented an analytical expression for Bishop's parameter v in terms of the saturated fraction and S r of the unsaturated fraction of the soil and used it to interpret shear strength. One issue with this approach is that v cannot be easily determined either experimentally or theoretically.…”

A probabilistic solid-porous model to determine the shear strength of unsaturated soils

“…In addition, the hypotheses made to interpret the results of this test are too rough [18]. This same deviation of the theoretical PSD with respect to the experimental results was observed when a computational model was used to simulate the RC of this material [11]. Once the PSD for each confining pressure has been established, the determination of the parameters of the model is completed.…”

“…The description of the solid-porous model can be found elsewhere [11]. In this paper only the main characteristics of the model are emphasized.…”

Bearing capacity factor, N γ , for unsaturated soils by ZEL method

“…There are many methods to obtain effective stress parameter from SWCC results, soil pore size distributions through a fractal model, or by a solid-porous model using soil pore size and grain size distribution as well as soil water retention curve [3,17,18,27]. Among many researchers suggesting different relationships, Khalili and Khabbaz [17] performed a review on the effective stress parameter of Bishop [4] …”

“…An effective (or equivalent) stress approach has been reported to be valid for prediction of unsaturated soil shear strength and therefore seems to be adequate for analyses [17,27]. Since the matric suction is an extra factor that contributes to the shear strength of unsaturated soils in comparison with saturated soils, the evaluation of the bearing capacity of unsaturated soils is a difficult task.…”