Abstract
Triaxial compression tests are a standard in geotechnical practice due to their usefulness in understanding the mechanical behaviour of the geomaterials and are often used to calibrate constitutive models.
When samples are reconstituted in the laboratory, the moist tamping method is usually used to control the global density while enabling the preparation of loose states; however, results from X-ray tomography reported in the literature suggest that the internal density profile entails inhomogeneities. Another important aspect is the lubrication of the end platens; rough ends can lead to dead zones and strain localization within the sample. These two aspects are rarely considered when calibrating constitutive model parameters, as Gauss point elemental tests are generally performed to fit the lab test results.
This paper presents a numerical investigation of the moist tamping technique and lubrication end platen effects on the undrained triaxial compression behaviour of the Hutchenson Sand. Sixteen cases are modelled using NorSand constitutive model for different lubrication conditions, sample preparation methods, and pre-shearing average state parameters.
Results show that they play a key role in the post-peak behaviour of the material and that Gauss point simulations can only be matched when the sample is perfectly uniform with lubricated ends.
Authors:
Mauro Sottile | SRK Consulting Argentina
Nicolás Labanda | SRK Consulting Australia
R.J. Cier | SRK Consulting Australia
D. Reid | University of Western Australia, Australia
A. Fourie | University of Western Australia, Australia
