[SSS14-P03] Mechanism controlling the frictional strength of quartz rocks at intermediate slip rates
Keywords:agate, silica gel, frictional strength, intermediate slip rates
Steady-state friction coefficient of agate μss was ≈0.6 at V = 1 mm/s, ≈0.5 at V = 7 mm/s, and ≦0.1 at V = 10 cm/s. T was ≈25°C at V = 1 mm/s, ≈30°C at V = 7 mm/s, and up to 85°C at V = 10 cm/s, but the actual temperature along the slip surface must have been much higher. μss of silica gel gouge was ≈0.7 at V = 1 mm/s, 0.4–0.5 at V = 7 mm/s, and ≦0.2 at V = 10 cm/s. T was 25–28°C at V = 1 mm/s, 30–37°C atV = 7 mm/s, and 80–100°C at V = 10 cm/s, but again, the actual temperature in the gouge layer must have been much higher.
Thus our results show that agate or silica gel exhibits weakening with increasing T, and that the presence of silica gel does not reduce the frictional strength when T is not high enough. Shear strength of quartz rocks is high so that significant amount of frictional heat would be produced at asperity contacts even at V ≈ 1 cm/s, which must be responsible for weakening of quartz rocks at intermediate slip rates.