The time dependence of friction of rock joints

TLDR: For the determination of the time dependent friction behavior on rock joints laboratory tests (in principle direct shear test) are conducted as mentioned in this paper, and the results show that the friction resistance depends on shear rate and relative movements.

Abstract: For the determination of the time dependent friction behaviour on rock joints laboratory tests (in principle direct shear test) are conducted. “Opalinuston” as a weak rock was used as test material. The tests are carried out under controlled strain conditions at different shear rates. The results show that the friction resistance depends on shear rate and relative movements. For constant relative movements and a constant normal stress a logarithmic relation between friction resistance and shear rate results. By determining the dependence of the viscoplastic friction on relative movement a creep curve can be deduced describing the friction behaviour of a joint in the examined time range.