Behaviour of normally consolidated clay at elevated temperature

Abstract

Not much has research work been done so far on temperature-related behaviour of clays. This theme has not received much attention of research workers in this field for a long time until the late 1960s when Campanella and Mitchell published their paper on "Influence of Temperature Variations on Soil Behaviour" in 1968 (Campanella and Mitchell, 1968). What followed was a special conference on this subject held in Washington in 1969, addressing a variety of research results in this field at that time. However, the interest of most research workers in the following two decades has been in soil models and their numerical implementation. Most research funds have been channelled towards studies concerning basic soil properties and the implementation of the results of research than to other topics in the same time. In recent years, rapid industrialization and implementation of many military technologies into civil industries have taken place in many western countries and a few other countries in Asia. This gave rise to a variety of problems related to the disposal of nuclear waste particularly in the late 1980s. A series of studies regarding disposal problems of nuclear waste were then carried out in Italy and the United States (Hueckel et al, 1990). In Australia, the first project related to this topic was awarded in 1991 to the Centre for Geotechnical Research (CGR) at School of Civil and Mining Engineering, University of Sydney. This thesis contains the results obtained from triaxial tests performed at different elevated temperatures using a new triaxial apparatus called HTTA (High Temperature Triaxial Apparatus) specially designed for and forming part of, the work in this research. The thesis also contains a comparison of the experimental results and the predictions by different Cam-clay models including the revised Camclay model developed in this research. Specimens of a remoulded clay, Kaolin CIC, have been tested at various I temperatures ranging from ambient temperature of 22±2°C to 100±5°C with two triaxial apparatuses. The first apparatus for tests at ambient temperature is a Bishop- Wesley-Type hydraulic triaxial apparatus; the other is a modified triaxial apparatus specially tailored and assembled for performing triaxial tests on the specimens at various elevated temperatures. The triaxial tests on the specimens were conducted at room temperature as well as at two elevated temperatures, namely 50°C and 100°C. Stress-strain response of the specimens at different temperatures was observed. Attempts have been made in different ways to investigate whether soil properties of the selected clay would change with temperature. Further, the attempts made were also to see what have been changed in the stress-strain behaviour of the clay at different elevated temperature. Then, the test results from different elevated temperatures were compared with those obtained from the tests at room temperature; and also compared with the predictions by the Cam-clay models.