On Deformation and Fracture of Granite Part III

Abstract

Creep of granite under compressional force was very accurately measured in the longitudinal and lateral direction with an electrical resistance strain gauge up to a time duration of 2, 000, 000 seconds.
The empirical equations connecting creep strain and time are
s=A+A₁e^-α₁t+A₂e^-α₂t+A₃e^-α₃t+Blogt+Ct
for the longitudinal direction, and
s=A+Blogt+Ct
for the lateral direction. The former is more or less unduratory and the later rectilinear.
In some cases, specimens ruptured in creeping. The creep curve for granite has three stages like those for ordinary materials, but, the curve has distinct discontinuities caused by micro cracks, and in the final stage, rupture starts from the cracks which occur one after another.