Influence of fracture geometry on shear behavior

Gentier, Sylvie; Riss, Joëlle; Archambault, G.; Flamand, Rock; Hopkins, Deborah

doi:10.1016/s1365-1609(99)00096-9

Cited by 116 publications

(50 citation statements)

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“…Their computer code was not available for this work. Methods based on visual investigation such as image analysis (Gentier et al 2000;Riss et al 1997). In these methods, the shear test has to be stopped and the joint surfaces opened for examination and photographing of the joint surfaces.…”

Section: Description Of the New Methods For Joint Surface Characterizamentioning

confidence: 99%

“…The shear mechanism of joints is strongly affected by the joint roughness, the loading conditions, and the mechanical properties of the rock (Barton 1973;Kulatilake et al 1995;Re and Scavia 1999;Gentier et al 2000;Yang et al 2001;Lopez et al 2003). The shear mechanism of rock joints is the basis of constitutive models for predicting the shear strength of rock joints.…”

Section: Introductionmentioning

confidence: 99%

“…Conversely, under low normal stresses, asperity degradation can arise if the shear displacement is large enough. Gentier et al (2000) developed a method using image processing techniques. They showed that the mechanical behavior of joints is strongly linked to the geometry of asperities.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, size, shape, and distribution of contact areas are related to the geometry of asperities, loading conditions, mechanical parameters of the rock, and shear displacement (Ladanyi and Archambault 1970;Hutson and Dowding 1990;Haberfield 1995, 2002;Gentier et al 2000;Grasselli and Egger 2003;Misra 2002;Karami and Stead 2008;Park and Song 2013). In this paper, a new mathematical method is presented in the form of a software to characterize the joint surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Geometric Effect of Asperities on Shear Mechanism of Rock Joints

et al. 2015

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Three-dimensional tracking of changes of asperities is one of the most important ways to illustrate shear mechanism of rock joints during testing. In this paper, the changes of the role of asperities during different stages of shearing are described by using a new methodology for the characterization of the asperities. The basis of the proposed method is the examination of the three-dimensional roughness of joint surfaces scanned before and after shear testing. By defining a concept named 'tiny window', the geometric model of the joint surfaces is reconstructed. Tiny windows are expressed as a function of the x and y coordinates, the height (z coordinate), and the angle of a small area of the surface. Constant normal load (CNL) direct shear tests were conducted on replica joints and, by using the proposed method, the distribution and size of contact and damaged areas were identified. Image analysis of the surfaces was used to verify the results of the proposed method. The results indicated that the proposed method is suitable for determining the size and distribution of the contact and damaged areas at any shearing stage. The geometric properties of the tiny windows in the pre-peak, peak, post-peak softening, and residual shearing stages were investigated based on their angle and height. It was found that tiny windows that face the shear direction, especially the steepest ones, have a primary role in shearing. However, due to degradation of asperities at higher normal stresses and shear displacements, some of the tiny windows that do not initially face the shear direction also come in contact. It was also observed that tiny windows with different heights participate in the shearing process, not just the highest ones. Total contact area of the joint surfaces was considered as summation of just-in-contact areas and damaged areas. The results of the proposed method indicated that considering differences between just-in-contact areas and damaged areas provide useful insights into understanding the shear mechanism of rock joints.

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Section: Description Of the New Methods For Joint Surface Characterizamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Geometric Effect of Asperities on Shear Mechanism of Rock Joints

et al. 2015

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“…The mechanical behaviour and flow properties of fractures depend largely on the surface roughness of their walls and their match (Barton and Choubey 1977;Gentier et al 2000;Crandall et al 2010): the walls of natural fractures are surfaces with ripples of different wavelengths that can be as much as the asperities directly associated with the minerals or component elements. In particular, Hopkins (2000) highlighted the determining role of the contact zone characteristics (shape, size, number, distribution and resistance) on the fracture's mechanical properties and of the structure of the free space between the walls (void space) on the hydraulic properties.…”

Section: Acquisition Of the Fracture's Morphological Featuresmentioning

confidence: 99%

Evolution of fracture permeability with respect to fluid/rock interactions under thermohydromechanical conditions: development of experimental reactive percolation tests

Blaisonneau¹,

Peter-Borie²,

Gentier³

2016

Geotherm Energy

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Geophysical Signatures of Shear‐Induced Damage and Frictional Processes on Rock Joints

et al. 2018

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In this study, ultrasonic waves recorded during direct shear experiments on rock joints were employed to investigate the shear failure processes. Three types of wave attributes were systematically observed prior to the shear failure of the rock joints: (a) maximum in the amplitude of the transmitted wave, (b) maximum in the dominant frequency of the transmitted wave, and (c) maximum in the velocity of the wave. Different processes occurring during both frictional sliding and stick‐slip oscillations were identified in this study: (a) interseismic phase and (b) preseismic phase. The interseismic phase is associated with elastic loading, very small local slip rate, and increasing ultrasonic transmission along the contact surfaces. The rock joint is considered locked, and the increase in ultrasonic transmission represents an increase in the real (true) area of contact because of interlocking and contact aging. The start of the preseismic phase is marked by the onset of precursors for different regions of the rock joint. Following the interseismic and preseismic phases, coseismic phase occurs. The coseismic phase begins with the reduction in the applied shear stress and is associated with an abrupt increase in the local slip rate. The reductions in transmitted amplitude, wave velocity, and dominant frequency all indicate the preseismic phase when the asperity contacts begin to fail before macroscopic frictional sliding. The observation of the preseismic phase in both the loading phase leading to stable sliding and stick‐slip failure modes suggests that microphysical processes of fault weakening may share key features for these two failure modes.

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Influence of fracture geometry on shear behavior

Cited by 116 publications

References 1 publication

Geometric Effect of Asperities on Shear Mechanism of Rock Joints

Geometric Effect of Asperities on Shear Mechanism of Rock Joints

Evolution of fracture permeability with respect to fluid/rock interactions under thermohydromechanical conditions: development of experimental reactive percolation tests

Geophysical Signatures of Shear‐Induced Damage and Frictional Processes on Rock Joints

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