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Title: Examination of the rate-state friction equations under large perturbations from steady sliding: A theoretical and experimental study.
Authors: Bhattacharya, Pathikrit
Advisors: Rubin, Allan M.
Contributors: Geosciences Department
Keywords: Earthquake Nucleation
Fault mechanics
Rate and State friction
Subjects: Geophysics
Secondary education
Issue Date: 2017
Publisher: Princeton, NJ : Princeton University
Abstract: The laboratory derived rate-state friction (RSF) relationships are the most widely used constitutive equations for fault friction in numerical models of fault mechanics. But even after more than three decades of these being first proposed, we are far from certain about the identity of the ‘proper’ set of these equations which describe all laboratory friction data. In fact, the two most popular choices of the ‘state’ evolution component of RSF represent two end-member physical pictures of how frictional strength evolves – with time even without slip (Aging law) or only with slip (Slip law). Yet both these view points have traditionally been inferred to be independently supported by different classes of friction experiments which (sometimes) access similar portions of the RSF parameter space. We present a set of comprehensive studies which establish, both theoretically and with inversion of laboratory data, that in fact all the widely used experimental protocols provide evidence that friction dominantly evolves with slip even when the interface is sliding at the lowest slip rates accessed by these experiments. We examined these state evolution laws under a diverse range of sliding conditions – up to 3.5 orders of velocity steps on both initially bare rock and gouge, up to 3X10^4 s long holds on initially bare rock performed using machine stiffnesses differing by 1.5 orders of magnitude and 5% normal stress steps on initially bare rock carried out at an order of magnitude different sliding rates. For all of these experimental regimes, the widely used Aging law generally performed worse than the Slip law, even in those parts of the parameter space where conventional RSF wisdom would have predicted it to find strong support. Additionally, across all these experiments, more recent prescriptions of state evolution were generally found to fit the data only as well as the Slip law even with the freedom of extra parameters. We argue that these findings contradict the traditional view that the state variable is a proxy for the ‘quantity’ of true contact area alone, it is likely that some measure of the ‘quality’ of contacts contributes significantly to state evolution as well.
Alternate format: The Mudd Manuscript Library retains one bound copy of each dissertation. Search for these copies in the library's main catalog:
Type of Material: Academic dissertations (Ph.D.)
Language: en
Appears in Collections:Geosciences

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