Influence of Stress Ratio and Stress Path on Behavior of Loose Decomposed Granite

Abstract

This paper presents results from four series of triaxial compression tests of loosely compacted decomposed granite (DG) or silty sand on both isotropically and anisotropically consolidated specimens. These tests included undrained tests, drained tests with constant deviator stress, and a decreasing mean effective stress path. The silty sand possessed high compressibility during isotropic compression. The observed high compressibility is probably attributed to the loose soil structure created by using the moist tamping method and the presence of crushable feldspar in the soil. Static liquefaction behavior and the so-called “reversed” sand behavior were observed in all undrained tests. This “reversed” sand behavior can be readily explained by the high compressibility of DG leading to the nonparallel and converging nature of the initial state line and the critical state line. Preshearing resulted in a more brittle response in the postpeak behavior. The higher the initial stress ratio