New Techniques for Rock Fracture Energy Measurements.
47th Ann Fall Mtg Soc Petrol Eng AIME San Antonio Texas, 10/8-11/72 SPE Preprint 4060 :6 pages
The use of closed-loop, servo-controlled test systems to obtain rock fracture energy measurements in uniaxial tension, torsion, and direct shear is described. Results of fracture energy tests performed on three rock types are presented. Analysis of the test results substantiates the usefulness of measuring fracture energy by the new test techniques. The advantage of these new tests, providing data potentially useful for input into analytical rock response calculations, far outweighs the advantage of the usual test methods--simplicity of test procedure. Fracture energy values for three rock types tested under a series of load configurations indicate that fracture energy requirements increase with confining stress level. The ratio of fracture energy required in uniaxial compression to that in uniaxial tension ranges from 140 for Berea sandstone to 560 for Barre granite.
47th Ann. Fall Mtg., Soc. Petrol. Eng., AIME, San Antonio, Texas, 10/8-11/72, SPE Preprint 4060