Effect of strain rates from 10-2 to 10 sec-1 in triaxial compression tests on three rocks

Abstract Room-temperature, compression tests at strain rates from 10-2 to 10 sec-1 have been run on Charcoal Granodiorite to 0.45 GPa confining pressure and on Berea Sandstone and Indiana Limestone to 0.25 GPa confining pressure. For each rock at each confining pressure, the differential stress at failure is relatively constant up to a strain rate of 1 sec-1 and apparently increases abruptly above this strain rate. Dynamic analysis of the testing apparatus inertia and does not reflect a real increase in the strength of the rocks. Taking inertia into account, the actual failure stresses of the three rocks are relatively independent of strain rate between 10-2 and 10 sec-1. Inthe same interval, the strains at which the unconfined rocks begin to fragment tent be lower at higher strain rates. The combination of decreasing strains and relatively constant stresses with increasing strain rate suggests that the energy necessary to fragment the unconfined rocks is lower at higher strain rates.