STRAIN RATE DEPENDENT MECHANICAL-PROPERTIES OF NEW-ALBANY REFERENCE SHALE

Drilling, mining and blasting of rock-like materials, in situ fracturing, rock fragmentation size and permeability extension are strongly affected by strain rates of loading. For low strain rates, fragment sizes are large, and cracks propagate further. For high strain rates, fragment sizes are small and cracks are localized. The purpose of the present investigation is to determine the effects of strain rate on the initial (linear) value of Young's modulus and on Poisson's ratio for different grades of New Albany oil shale, a reference oil shale designated by the U.S. Department of Energy. Material anisotropy is considered. Cylindrical specimens cored in a particular orientation of the oil shale formation are tested in compression, and the rate effects are investigated. An efficient data acquisition/reduction system is developed, interfacing with an Instron closed-loop hydraulic testing machine. Strain gauge instrumentation is used to measure lateral and longitudinal strains. Strain rates of about 10-5-100/sec are studied. © 1990.