Analysis of Cavity Expansion in Sand

Abstract

Cavity expansion analysis plays a significant role in modern soil mechanics. The analysis of many of the most important problems in the practice of geotechnical engineering (such as cone penetration testing, pile loading, or pressuremeter testing) rely to a large extent on cavity expansion analyses. Cavity expansion processes are of two basic types: expansion from a finite radius and expansion from zero initial radius. It is usual to use a different type of analysis for each of these problems. Analysis of the cavity creation problem yields only the limit pressure, but not necessarily information on the pressure‐strain relationship during expansion. Analysis of expansion from an initially finite cavity radius gives a pressure‐strain curve, but no information on the limit pressure. In this article, we present a simple numerical analysis that provides the solution to both problems simultaneously. The analysis takes full account of the flow rule and dependence of the friction angle on stress state, providing a rigorous solution for the cavity expansion problem throughout the plastic zone. The analysis can be used for both spherical and cyclindrical cavities. As illustration of the versatility of the analysis, plots of limit pressure versus soil state, cavity pressure versus strain for various soil states, and evolution of soil state within the plastic zone are provided.