The effect of cyclic stress on dilatancy: Another look

Twelve granite and gabbro cylinders have been stress-cycled under confining pressures of 0.5, 1.5, and 5.0 kbar. No consistent trend appeared in the minimum stress required for dilatancy as a function of cycle number at the highest pressure, but at 1.5 kbar and below a decrease was indicated. Dilatant volumetric strain at differential stresses corresponding to the frictional strength of the rock persists at a value of a few parts in 104 at all confining pressures and is essentially unaffected by cycling.