Author(s)

M. Fauziah & H. R. Nikraz

Abstract

The behaviour of unsaturated soil is quite different from those of saturated soil because of the influence of suction. Although soils are generally assumed fully saturated below the groundwater table, they may be semi saturated near the state of full saturation under certain conditions. The situation of partial saturation may be caused by several factors, such as variation of water table level due to natural or manmade processes. This study was undertaken to delineate the effects of soil water suction on the behaviour of kaolin clay under plane strain condition, as more geotechnical problems in the field such as slope failure, earth retaining structures, and shallow foundation basically occur in plane strain conditions rather than tri axial condition. The biaxial apparatus, which was used in this study, is a modification of the conventional tri axial apparatus. Cell pressure from the tri axial compression test and a rigid loading platen are used to apply the minor (σ3) and major (σ1) principle stresses, respectively, to the clay specimen. The specimen is mounted inside the device, which fully restrains any out-of-plane deformation by the use of a pair of rigid perspex wall. The volume change of the sample was measured by local strain devices and laser sensor while the water volume change was recorded by a volume gauge. Results from the tests were compared with the theoretical analysis within the elasto-plastic critical state model for unsaturated soil. Keywords: biaxial, partly saturated, matric suction, volume change.

Keywords

biaxial, partly saturated, matric suction, volume change.