Interpretation of stress paths from pressuremeter tests in sand

This paper presents a method to obtain the constitutive relationships of sands from in-situ drained self-boring pressuremeter tests. Plane-strain conditions and Rowe's stress-dilatancy theory are assumed to hold to determine effective stress paths. The proposed method appears to correctly render the response behavior of loose to dense sands. The two parameters that are needed to interpret the pressuremeter expansion curves are the initial effective horizontal pressure at rest, sigma'(ho), and the effective friction angle of the sands at constant volume, phi'(cv) The proposed method allows to draw drained stress paths on a Mohr-Coulomb diagram, from which both the peak friction angle phi'(p) and the peak dilatancy angle v'(p) may be determined. In addition, as Rowe's dilatancy theory is used in the analyses, it is possible to obtain the variation of the volumetric strain as a function of the shear strain. Finally, for the numerical solution procedure followed in the paper, the original pressuremeter curves used were first discretized and then approximated with a polynomial of degree 4 to 5. This allowed to considerably reduce the scatter in the results.