Liquefaction resistance of soils with differing pumice content

Abstract

Pumice rich soils are found across large areas of the North Island of New Zealand. In many cases, these deposits are derived from recent volcanic eruptions in the Taupo Volcanic Zone. Pumiceous soils are characterized by their vesicular nature, which leads to the grains being lightweight, crushable, and having an extremely rough and angular surface texture. These properties give pumiceous soils particular engineering properties which are distinct from more commonly encountered hard-grained materials and make them problematic for engineers interested in assessing the risk and potential consequences of liquefactions. Natural pumice-rich soils are found with varying amounts of pumice; however, it remains unclear on how the amount of pumice present in a soil mixture alters the behavior. In this paper, three materials, obtained from the same parent material, are considered: a hard-grained sand, a pumiceous sand, and a mixture of the two. These materials were tested using a cyclic triaxial apparatus to determine the features of liquefaction resistance. It is shown that a reduction in cyclic resistance was observed due to the presence of pumice. Moreover, the majority of this effect appears to occur a relatively high portions of pumice in the soil.