Humidity dependence of AE activity in sheared quartz gouges and its implication for the micromechanics of friction

Abstract The micromechanics of friction has been investigated from the viewpoint of the healing of real contacts. In this study, the underlying processes of friction are discussed from the viewpoint of the contact junction deformation and failure by measuring the acoustic emission (AE) activity asso...

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Main Author: Yasuo Yabe
Format: Article
Language:English
Published: SpringerOpen 2025-01-01
Series:Earth, Planets and Space
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Online Access:https://doi.org/10.1186/s40623-024-02132-2
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author Yasuo Yabe
author_facet Yasuo Yabe
author_sort Yasuo Yabe
collection DOAJ
description Abstract The micromechanics of friction has been investigated from the viewpoint of the healing of real contacts. In this study, the underlying processes of friction are discussed from the viewpoint of the contact junction deformation and failure by measuring the acoustic emission (AE) activity associated with the frictional sliding. Sliding-rate step tests of synthetic quartz gouges sandwiched between metal forcing blocks are conducted using a low-speed (< 700 μm/s) rotary shear apparatus. Humidity is controlled to be dry (~ 5%RH), room (~ 40%RH), humid (100%RH), or wet (saturated without pore pressure control). The frictional behavior is modeled by the rate- and state-dependent friction (RSF) law with two state variables. Shorter critical slip distances of the state evolution would be about the contact junction size, while longer critical slip distances are close to the average diameter of gouge particles. The AE activities are evaluated by AE rate that is the number of AE events per unit sliding distance and the m-value that characterizes the amplitude distribution. As variations in AE activities and the evolution term ( $${b}_{1}$$ b 1 ) with the shorter critical slip distance highly correlate, AE activity may reflect the state of contact junction. While $${b}_{1}$$ b 1 increases with increasing water vapor from dry to humid, AE rate and the m-value are decreased. This may be caused by an increase in inelasticity of the contact junction deformation. Under wet conditions, $${b}_{1}$$ b 1 is similar to that under the humid condition, AE rate is further decreased but the m-value becomes significantly large. This is probably because the failure process of the contact junction changes to less brittle one, implying the impact of phase of water (vapor or liquid) on the brittleness of the failure processes of contact junction. Graphical Abstract
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spelling doaj-art-1e05d682f8a84afe8d6be733cec881f02025-01-19T12:13:30ZengSpringerOpenEarth, Planets and Space1880-59812025-01-0177111110.1186/s40623-024-02132-2Humidity dependence of AE activity in sheared quartz gouges and its implication for the micromechanics of frictionYasuo Yabe0Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku UniversityAbstract The micromechanics of friction has been investigated from the viewpoint of the healing of real contacts. In this study, the underlying processes of friction are discussed from the viewpoint of the contact junction deformation and failure by measuring the acoustic emission (AE) activity associated with the frictional sliding. Sliding-rate step tests of synthetic quartz gouges sandwiched between metal forcing blocks are conducted using a low-speed (< 700 μm/s) rotary shear apparatus. Humidity is controlled to be dry (~ 5%RH), room (~ 40%RH), humid (100%RH), or wet (saturated without pore pressure control). The frictional behavior is modeled by the rate- and state-dependent friction (RSF) law with two state variables. Shorter critical slip distances of the state evolution would be about the contact junction size, while longer critical slip distances are close to the average diameter of gouge particles. The AE activities are evaluated by AE rate that is the number of AE events per unit sliding distance and the m-value that characterizes the amplitude distribution. As variations in AE activities and the evolution term ( $${b}_{1}$$ b 1 ) with the shorter critical slip distance highly correlate, AE activity may reflect the state of contact junction. While $${b}_{1}$$ b 1 increases with increasing water vapor from dry to humid, AE rate and the m-value are decreased. This may be caused by an increase in inelasticity of the contact junction deformation. Under wet conditions, $${b}_{1}$$ b 1 is similar to that under the humid condition, AE rate is further decreased but the m-value becomes significantly large. This is probably because the failure process of the contact junction changes to less brittle one, implying the impact of phase of water (vapor or liquid) on the brittleness of the failure processes of contact junction. Graphical Abstracthttps://doi.org/10.1186/s40623-024-02132-2Rate-step test of quartz gougesRotary shear testMicromechanics of frictionRate- and state-dependent frictionAcoustic emission activityHumidity dependence
spellingShingle Yasuo Yabe
Humidity dependence of AE activity in sheared quartz gouges and its implication for the micromechanics of friction
Earth, Planets and Space
Rate-step test of quartz gouges
Rotary shear test
Micromechanics of friction
Rate- and state-dependent friction
Acoustic emission activity
Humidity dependence
title Humidity dependence of AE activity in sheared quartz gouges and its implication for the micromechanics of friction
title_full Humidity dependence of AE activity in sheared quartz gouges and its implication for the micromechanics of friction
title_fullStr Humidity dependence of AE activity in sheared quartz gouges and its implication for the micromechanics of friction
title_full_unstemmed Humidity dependence of AE activity in sheared quartz gouges and its implication for the micromechanics of friction
title_short Humidity dependence of AE activity in sheared quartz gouges and its implication for the micromechanics of friction
title_sort humidity dependence of ae activity in sheared quartz gouges and its implication for the micromechanics of friction
topic Rate-step test of quartz gouges
Rotary shear test
Micromechanics of friction
Rate- and state-dependent friction
Acoustic emission activity
Humidity dependence
url https://doi.org/10.1186/s40623-024-02132-2
work_keys_str_mv AT yasuoyabe humiditydependenceofaeactivityinshearedquartzgougesanditsimplicationforthemicromechanicsoffriction