Micromechanical‐based experimental and analytical studies on rate effects and stick‐slip instability of smooth quartz surfaces in the presence of plastic and non‐plastic gouges

Abstract

We examined with micromechanical-based experiments the influence of shearing rate on the tangential contact behavior of smooth (very low surface roughness) flat quartz surfaces with montmorillonite and crushed aggregates as gouges. On decreasing the shearing rate by one order of magnitude, significant changes in the stick-slip instability were observed; increase in force-drop, recurrence interval and slip velocity. The initial tangential stiffness increased on decreasing the shearing rate. The type of gouge particles also influenced the behavior of the interfaces; for example, higher friction and stable sliding were observed for angular particles (non-plastic gouge) compared to flaky particles (plastic gouge). The partition of the tangential force-displacement relationship based on the shape of the curve was also dependent on the shearing rate. On a qualitative standpoint, the results presented in this micromechanicalbased study were in agreement with macro-scale test results published in the literature, although different scale tests were also performed in the present work, from grain-level to direct shear test size. The changes in the behavior of stick and slip components of the tangential force and the contact area with shearing rate were analytically studied, and the corresponding variations in the normal load-displacement relationship were also discussed. This experimental micromechanical-based study with additional analytical support, provides a preliminary understanding of the frictional behavior of different gouges under shearing rates of one folder difference and also provides insights into the stickslip instability behavior at a microscopic (grain-scale) standpoint.

DEM Analyses of Cemented Granular Fault Gouges at the Onset of Seismic Sliding: Peak Strength, Development of Shear Zones and Kinematics

“…The main slipping zone can contain cohesive or non-cohesive wear material (Rice & Cocco, 2002), and a micrometre-millimetre scale ''slip distance'' is observed. The granular literature related to fault mechanics often explores stickslip instabilities, considering strain energy storage either at grain-scale (Dorostkar et al, 2018;Leeman et al, 2015) or in the loading system (Kasyap & Senetakis, 2021). Although such energy storage is not present in our simulation, it is to be kept in mind from the perspective of upscaling the frictional behaviours we report to actual fault systems.…”

Influence of Grain‐Scale Properties on Localization Patterns and Slip Weakening Within Dense Granular Fault Gouges

“…Fault mechanics often explores stick‐slip instabilities, considering strain energy storage either at the grain scale (Dorostkar et al., 2018; Leeman et al., 2015) or in the loading system (Kasyap & Senetakis, 2021), and shearing experiments can thus be carried out in a stable or unstable way. In our model, the sliding is imposed by a shearing velocity, and the non‐deformability of the rock does not allow a proper energy storage within the fault system.…”

Experimental Study on Interfacial Friction Characteristics of Reinforced Clay

“…The results of this test show that sisal fiber and PVAc possess the interfacial coupling property of soil to differing extents. The adhesion ability depends on the contact area and the roughness between the sample and the interface [ 40 ]. Resulting from the sisal fibers’ rough surface and good physical resistance ability, it effectively increased the friction characteristics between clay and rock.…”