An overview of the University College Dublin hollow cylinder apparatus

Abstract

Most sedimentary soils are inherently ansiotropic. Their response to loading will depend on the directions of the principal stresses. In most geotechnical problems the principal stresses gradually rotate during loading. As a consequence, deformations occur due to both change in the magnitude and change in the direction of the principal stresses. The Hollow Cylinder Apparatus (HCA) is the only soil test device that can facilitate independent control of both the magnitude and the direction of the principal stresses. The stress history and loading conditions at a point in a soil deposit can be reproduced on a hollow cylindrical specimen and its constitute behaviour and pore pressure response measured. This paper is divided into two sections: First, an example showing the influence of the principal stresses on the strength and deformation characteristics of a soil is discussed. Second, an overview of a unique HCA currently being commissioned in the Department of Civil Engineering, University College Dublin (UCD) is presented. The operating principles and the instrumentation used to load the sample and measure its deformational response are discussed.