Expansive Soil Test Site Near Newcastle

Abstract

A field site was established in 1993 near Newcastle, Australia, as part of a long-term study into expansive soil behavior. The primary objectives in establishing the site were to collect high quality data with which to check current design methods for lightly loaded building foundations and to develop improved understanding of the physical processes that drive unsaturated expansive soil behavior. The site was instrumented to allow measurement of soil water content, soil moisture suction, and ground movement to depths of 3 m. The site was provided with two ground covers to simulate moisture boundary conditions due to the presence of typical structures. This paper presents some of the more important findings from the 7 years of data acquired so far. These include a qualitative assessment of the overall site behavior, and quantitative observations of the range of total suction and water content changes with depth, the depth to which moisture changes occur, and the contributions to surface movement from ground movement at various depths. The shape of a mound developed beneath a flexible cover on an initially dry site is examined, and the effects of a large tree on moisture changes are reported.