Effect of stress level on cyclic resistance of undisturbed samples of pumiceous soil

Abstract

Geologically recent volcanic eruptions from the Taupo Volcanic Zone (TVZ) have resulted in the deposition of pumice materials across significant areas on the North Island of New Zealand. In particular, these volcanically derived materials are often encountered on engineering projects in the areas of Hamilton and Tauranga. Pumiceous soils are problematic from a geotechnical perspective due to their high crushability and low weight. These properties mean that practicing engineers must exercise extreme caution when these soils are encountered on a project, since these soils are not captured in the existing databases used to develop the correlations between parameters of engineering interest and in-situ characterisation techniques. The crushable nature of the pumiceous material introduces some interesting questions surrounding the cyclic behaviour of these soils at different stress levels; whether increased stress levels results in significantly different cyclic resistance, and whether this change will result in increased or decreased strength. This poster will present results from a recent sampling campaign where pumice rich materials were obtained from a site close to the town of Edgecumbe in the North Island. The poster will discuss results from a suite of triaxial tests which aimed to examine the effects of initial effective stress level on the cyclic resistance of soil layer with a moderate pumice content.