# Anisotropic-Isotropic undrained strenght ratio of normally consolidated clays

A laboratory determination of the in situ or k0-undrained compression strength of normally consolidated clays requires clay specimens to be anisotropically reconsolidated under conditions of zero lateral strain to their assumed in situ stresses before shear to failure.

However, since the relevant test, i.e, the lqyconsolidated undrained compression (CkoUC) triaxial test is a difficult and time-consuming one, it is routine practice to use the simpler consolidated isotropic undraincd compression (CIUC) triaxial test, empirically assuming that the strengths

A laboratory determination of the in situ or k0-undrained compression strength of normally consolidated clays requires clay specimens to be anisotropically reconsolidated under conditions of zero lateral strain to their assumed in situ stresses before shear to failure.

However, since the relevant test, i.e, the lqyconsolidated undrained compression (CkoUC) triaxial test is a difficult and time-consuming one, it is routine practice to use the simpler consolidated isotropic undraincd compression (CIUC) triaxial test, empirically assuming that the strengths

thus evaluated coincide in the two tests.

This paper describes an analytical simplification, derived from Critical State Soil Mechanics, which – still without resorting to a Ck0UC test – allows a more rational determination to be made of the undrained compression shear strength and hence of the normalized ratio and which is reasonably accurate for practical purposes. The proposed procedure requires only two parameters, namely Skempton’s pore pressure coefficient A and the friction angle, both obtainable from a single CIUC test.

A labora …

AUTORI: Federico A.
RIG ANNO:1987 NUMERO:4
Numero di pagine: 201