Soil Vision (SV Flux/SV Solid) consolidation modelling.

SVFLUX/SVSOLID has currently implemented a number of ways to relate the void ratio to the effective stress including: power and extended power functions, as well as Weibull and logarithmic functions. There is also included support for a dual power function to be specified, where different functions are applied over specific void ratio ranges. These functions can be used to closely fit the measured laboratory data especially in the low effective stress range. 

An Extended Power Function includes constants A,B and Z. Where A and B are constants governing the shape of the power function. Z  is an additional parameter having stress units to describe the gain in strength affecting the initial part of the power function. The Z parameter represents the effective stress at which the ‘initial’ void ratio occurs. In a situation such as that tested in the laboratory, the initial condition is one of equal total stress and pore-water pressure so that the effective stress is zero. The initial void ratio can be obtained from the extended power function by setting the effective stress to 0 and calculating the corresponding void ratio. This simulates the void ratio at the boundary between sedimentation and consolidation. The same constitutive equations relating hydraulic conductivity and compressibility as the Gibson et al. (1967) formulation are used to relate the material behavior.

If the initial void ratio at zero effective stress from the extended power function is different than the one measured for zero effective stress then there will be some differences in the obtained results compared to the measured results. The initial stress limit may aid in this case as it is the minimum stress that can be modeled. Any initial void ratios higher than this corresponding value will not affect the output if the void ratio-effective stress relationship beyond the initial stress limit is identical.