Akademik Veri Yönetim Sistemi
7th International Symposium on Deformation Characteristics of Geomaterials, Glasgow, İngiltere, 26 - 28 Haziran 2019
Poisson’s ratio () of rock specimens can be experimentally determined from radial deformation
measurements in an unconfined compression test. This is commonly achieved by mounting a compressometer
with diametric or perimetric measurement capability, both of which assume the specimen cross-section remains
a circle. If there is anisotropy among the horizontal directions, this assumption fails and measurements err. In
this study, a compressometer with three radial deformation measurements is developed. The accuracy of new
compressometer in determining the mean of the two values along the two axes of anisotropy is theoretically
investigated, assuming the deformed specimen is an ellipse in cross-section. Then, to capture separate values
along the axes of anisotropy, data from actual tests employing the new device were analysed in two different
approaches: Assuming the centroid of the cross-section remains stationary (1) does not produce physically
reasonable results. Assuming the specimen moves laterally and values are constant (2) is possible through a
grid search-type optimization algorithm. This results in calculation of the orientation of axes of anisotropy with
respect to the compressometer, as well as the corresponding values.