STATE PARAMETER FROM SELF-BORING PRESSUREMETER TESTS IN SAND

The present paper provides an analysis of self-boring pressuremeter tests in sand in terms of the state parameter. The method developed herein can be used to determine the in-situ sand state from the results of the self-boring pressuremeter test. Unlike the conventional drained pressuremeter analyses that almost exclusively use an elastic-perfectly plastic model, the new analysis is based on a strain-hardening (or softening) plasticity model in which the angles of friction and dilation are assumed to be a function of the state parameter. The numerical results presented suggest that there is a unique linear correlation between the loading slope of pressuremeter curves and the initial state parameter of the soil. It is therefore possible to deduce the state parameter of the sand from the measured pressuremeter loading slope. The relevance of this new analysis has been confirmed by the results of the pressuremeter test carried out in large calibration chambers.