Effect of Specimen Size on Confined Compression Testing of Rock Cores
Final technical rept. 29 Dec 1970-29 Dec 1971
IIT RESEARCH INST CHICAGO IL
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An experimental study was conducted to determine the influence of specimen size on the mechanical response of rock. Specimens of Charcoal Black granite Cold Spring, Minnesota and Indiana Limestone Bedford, Indiana ranging in size from 2-in. dia. to 36-in. dia. 32-in. dia. for the granite were tested in triaxial compression. Test data included axial and circumferential strain at up to 30 locations on the largest specimens, and axial and radial stresses. Data for loading, unloading and reloading conditions were collected. The loading data were fit to models describing bulk modulus and shear modulus, from which other moduli were determined. The reduction in strength over the size range and confining pressures employed ranged from 20 to 50 percent.
- Geology, Geochemistry and Mineralogy