Time-scales for the redistribution of stress in the course of pressuremeter creep tests in permafrost

摘要

This study deals with nonlinear creep and the time taken for completion of the stress redistribution process within a borehole scenario. Specifically, the pressuremeter test, with emphasis on a step loading of long duration, in ice saturated frozen soils is analyzed. A closed form stationary creep solution based on the model of a thick cylinder under plane strain condition, that considers large strains, is first developed. Subsequently non-stationary creep finite element analyses were carried out via this model and an assumption-relaxed model that considers the actual geometry of a typical pressuremeter test (where the net cavity pressure is applied only on a portion of the borehole cavity). Finally estimates of the extent to which stress redistribution occurs is numerically considered by revisiting classical theories and proposing a time scale by introducing a redistribution index, RI. (C) 2016 Elsevier B.V. All rights reserved.