An interpretation of thermo-mechanical behaviour of peat under 1-D compression

¹ Hokkaido University, Graduate School of Engineering, Kita-13 Nishi-8, Kita-Ku, Sapporo, Japan
² Hokkaido University, Faculty of Engineering, Kita-13 Nishi-8, Kita-Ku, Sapporo, Japan
³ Akita College, Department of Civil Engineering and Architecture, National Institute of Technology, 1-1, Iijima-Bunkyo-Cho, Akita, Japan

^* Corresponding author: kouchi.taishi.h8@elms.hokudai.ac.jp

Abstract

The one-dimensional thermo-mechanical behaviour of two peats was investigated through consolidation tests, including incremental loadings and constant-rate-of-strain loadings, under a variety of temperature-stress conditions. As an appropriate expression of highly compressible materials, the natural strain was employed instead of conventional engineering strain, which eliminates the apparent stress dependency of the compression index and the coefficient of secondary compression. Test results suggest the applicability of an isotach approach to the two peats used in this study. The temperature dependency of the coefficient of secondary compression defined with natural strain, λ^*_α, is very small. All the results summarized on the effective stress-strain plane show that there exists a unique Normal Compression Line (NCL) corresponding to each combination of temperature and strain rate. The NCLs are parallel to each other. Finally, in an attempt to construct a constitutive model, the temperature dependency of the NCL was quantified by introducing a constant, λ^*_T. By using the two parameters, λ^*_α and λ^*_T, which describe the strain rate- and temperature-dependent characteristics, respectively, a 1-D thermo-mechanical behaviour observed in this study will be modelled in a simple manner.