• The Journal of Engineering Geology
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• v.6 no.2
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• pp.103-110
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• 1996

This study shows the variation of poisson's ratio according to stress for the Cretaceous sandstones and shale in the Euiseoung Subbasin. To make a mechanical experiment, samples prepared with 3.0 cm in diameter and 6.2 cm in length were used in testing stress and strain. Generally poisson's ratio has been considered as one of properties, but contrary to steel, the test result makes sure that poisson's ratio has functional relation to stress. I had used four methods to calculate poisson's ratio, Poisson's ratio shows considerable different results according to the calculating, method but it has similar tendency in an elastic limit. Poisson' s ratio increases rapidly and is distinguished clearly in internal fracture region according to the calculating method. Poisson's ratio of sandstone and shale is different from one another in low and high stress regimes,but it is linearly proportional to the stress in an elastic regimes, that is, ${\nu}_t={\;}{\nu}_0+P_{\sigma}({\nu}_0$:first stage Poisson's ratio, ${\nu}_t$:poisson's ratio, P: poisson's coefficient, $\sigma$:stress). Poisson's ratios of two kinds of rock samples show continuous variation from 0.1 to 0.21 in an elastic regime. The variation of poisson's ratio is much wider in an internal fracture regine. It varies from 0.22 to 0.45 in sandstone, which is out of elastic regime.