... developed sufficiently far, will the concept of cracks apply to a high porosity chalk material. Figure Il Illustration of failure mechanisms 5 RING TESTS When it became clear that the direct tests would un- derestimate the tensile strength, it was' thought worthwhile to investigate the potential of the ring...

... ABSTRACT : The modified ring test was used to determine the mode I fracture toughness of bedrock cores from the Department of Energy Oak Ridge Reservation in east Tennessee. Low porosity sandstones, limestones, and dolostones from the lower part of the Paleozoic section in the Copper Creek...