The static and dynamic elasticity constants of sandstone and shales from the hard coal mine “Jasmos” determined in the laboratory conditions

The article presents a comparison of static and dynamic elasticity constants of sandstones and shales based on an uniaxial compression test. The results of the test indicated that the static elasticity constants are generally more sensitive to changes in stress than their dynamic equivalents. It was also demonstrated that within the full range of applied stresses the dynamic Young’s modulus is about twice as high as its static equivalent and reaches the maximum value for stresses for which a specimen volume is minimal. In the case of Poisson’s ratio it turned out its dynamic and static values are closely approximate for stresses which do not exceed 40% of the specimen strength limit. After crossing that limit the static ratio values increase rapidly whereas the dynamic ratio values change only to a slight degree.