Application of rate-and-state friction laws to creep compaction of unconsolidated sand under hydrostatic loading conditions

Paul N. Hagin, Norman H. Sleep, & Mark D. Zoback

Published May 2007, SCEC Contribution #946

Rate-and-state variable friction laws describe the time-dependent fault-normal compaction that occurs during holds in slide-hold-slide friction tests on unconsolidated materials. This time-dependent deformation is qualitatively similar to that observed during volumetric creep strain tests on unconsolidated sands and shales under hydrostatic loading conditions. To test whether rate-and-state friction laws can be used to model volumetric creep processes in unconsolidated sands, the rate-and-state formulation is expanded to include deformation under hydrostatic stress boundary conditions. Results show that the hydrostatic stress form of the rate-and-state friction law successfully describes the creep strain of unconsolidated sand. More importantly, values obtained for rate-and-state friction parameters by fitting these data are in the same range as those obtained from more traditional tests by fitting the fault-normal compaction of simulated gouge during a hold in a laboratory friction experiment.

Key Words
sand, soil mechanics, experimental studies, clastic sediments, loading, friction, boundary conditions, compaction, laboratory studies, creep, time factor, volume, sediments, unconsolidated materials, hydrostatic pressure

Citation
Hagin, P. N., Sleep, N. H., & Zoback, M. D. (2007). Application of rate-and-state friction laws to creep compaction of unconsolidated sand under hydrostatic loading conditions. Journal of Geophysical Research: Solid Earth, 112(B05420). doi: 10.1029/2006JB004286.