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Jian Zhao - One of the best experts on this subject based on the ideXlab platform.
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an shpb test study on wave propagation across Rock masses with different contact area ratios of Joint
International Journal of Impact Engineering, 2017Co-Authors: Jianchun Li, N N Li, Huaixing Li, Jian ZhaoAbstract:Abstract The Split Hopkinson Pressure Bar (SHPB) apparatus was adopted to investigate the influence of Joint contact area and spatial geometry of Joint surface on the dynamic property of Rock Joint and wave propagation. The specimen was comprised of two Rock cylinders. The top surfaces of the two cylinders contacted with each other, and their bottom surfaces contacted with the input and output bars of the SHPB apparatus, respectively. One top surface of one cylinder was sawn to shape a number of notches, while the other surfaces of the two cylinders were smooth and flat. The artificial Rock Joint was modeled as the contacted top surfaces of the two cylinders. The area ratio of contact between Joint surfaces equals to the Joint matching coefficient (JMC). The incident, transmitted and reflected waves were recorded from the strain gauges mounted on the input and output bars. Then, the transmission and reflection coefficients for strain wave propagation across the Rock specimen were obtained. Based on the basic theory of SHPB tests, the stress on the specimen, the deformation of Rock specimen and the stress-closure relation of Joint were analyzed. The experimental results show that the JMC and the spatial geometry of Joint surface affect not only the dynamic behavior of Joint but also the stress wave propagation.
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analytical time domain solution of plane wave propagation across a viscoelastic Rock Joint
Rock Mechanics and Rock Engineering, 2017Co-Authors: Jianchun Li, Lyesse Laloui, Jian ZhaoAbstract:The effects of viscoelastic filled Rock Joints on wave propagation are of great significance in Rock engineering. The solutions in time domain for plane longitudinal (P-) and transverse (S-) waves propagation across a viscoelastic Rock Joint are derived based on Maxwell and Kelvin models which are, respectively, applied to describe the viscoelastic deformational behaviour of the Rock Joint and incorporated into the displacement discontinuity model (DDM). The proposed solutions are verified by comparing with the previous studies on harmonic waves, which are simulated by sinusoidal incident P- and S-waves. Comparison between the predicted transmitted waves and the experimental data for P-wave propagation across a Joint filled with clay is conducted. The Maxwell is found to be more appropriate to describe the filled Joint. The parametric studies show that wave propagation is affected by many factors, such as the stiffness and the viscosity of Joints, the incident angle and the duration of incident waves. Furthermore, the dependences of the transmission and reflection coefficients on the specific Joint stiffness and viscosity are different for the Joints with Maxwell and Kelvin behaviours. The alternation of the reflected and transmitted waveforms is discussed, and the application scope of this study is demonstrated by an illustration of the effects of the Joint thickness. The solutions are also extended for multiple parallel Joints with the virtual wave source method and the time-domain recursive method. For an incident wave with arbitrary waveform, it is convenient to adopt the present approach to directly calculate wave propagation across a viscoelastic Rock Joint without additional mathematical methods such as the Fourier and inverse Fourier transforms.
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experimental study on wave propagation across a Rock Joint with rough surface
Rock Mechanics and Rock Engineering, 2015Co-Authors: Jian Zhao, X Chen, Jiazhou LiAbstract:Joints are an important mechanical feature of Rock masses. Their effect on wave propagation is significant in characterizing dynamic behaviors of discontinuous Rock masses. An experimental study on wave propagation across artificial Rock Joint was carried out to reveal the relation between the transmission coefficient and the contact situation of the Joint surface. The modified split Hopkinson pressure bar apparatus was used in this study while all the bars and specimens were norite cored from the same site. One surface of the specimens with a number of notches was adopted to simulate the artificial rough Joint. Two strain gauges were mounted on each pressure bar at a specific spacing. The incident, reflected and transmitted waves across the Joints were obtained using a wave separation method. Comparisons of the transmission coefficients were made under two different conditions: with the same Joint thickness but different contact area ratios, and with the same contact area ratio but different Joint thicknesses. The results show the effects of contact area ratio and thickness of Joints on wave transmission.
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stress wave interaction with a nonlinear and slippery Rock Joint
International Journal of Rock Mechanics and Mining Sciences, 2011Co-Authors: Jianchun Li, Jian ZhaoAbstract:Keywords: Deformational Behavior ; Parallel Fractures ; Single Fractures ; Shear-Strength ; Elastic-Waves ; Transmission ; Propagation ; Attenuation ; Boundary ; Model Reference EPFL-ARTICLE-171633doi:10.1016/j.ijrmms.2010.11.013View record in Web of Science Record created on 2011-12-16, modified on 2016-08-09
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three phase medium model for filled Rock Joint and interaction with stress waves
International Journal for Numerical and Analytical Methods in Geomechanics, 2011Co-Authors: Jianchun Li, Jian ZhaoAbstract:A three-phase medium model is proposed in describing the dynamic property of filled Rock Joints and an analytical study on longitudinal wave transmission normally across a three-phase Rock Joint is presented. Parameters in the three-phase medium model were determined by a series of modified split Hopkinson pressure bar (SHPB) tests, where a sand or clay layer was used to represent an artificially filled Rock Joint. The effect of the unloading path on the transmitted wave was discussed by comparing the analytical and SHPB test results. The derived wave transmission coefficients across the filled Joint agreed very well with those from the test results. Both the analytical and the test results showed that the wave transmission coefficients were affected by the mechanical properties of the fillings. Parametric studies with respect to the volume ratios of water and air in the three-phase medium and the type of filling material have also been performed. Copyright (C) 2010 John Wiley & Sons, Ltd.
Jianchun Li - One of the best experts on this subject based on the ideXlab platform.
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an shpb test study on wave propagation across Rock masses with different contact area ratios of Joint
International Journal of Impact Engineering, 2017Co-Authors: Jianchun Li, N N Li, Huaixing Li, Jian ZhaoAbstract:Abstract The Split Hopkinson Pressure Bar (SHPB) apparatus was adopted to investigate the influence of Joint contact area and spatial geometry of Joint surface on the dynamic property of Rock Joint and wave propagation. The specimen was comprised of two Rock cylinders. The top surfaces of the two cylinders contacted with each other, and their bottom surfaces contacted with the input and output bars of the SHPB apparatus, respectively. One top surface of one cylinder was sawn to shape a number of notches, while the other surfaces of the two cylinders were smooth and flat. The artificial Rock Joint was modeled as the contacted top surfaces of the two cylinders. The area ratio of contact between Joint surfaces equals to the Joint matching coefficient (JMC). The incident, transmitted and reflected waves were recorded from the strain gauges mounted on the input and output bars. Then, the transmission and reflection coefficients for strain wave propagation across the Rock specimen were obtained. Based on the basic theory of SHPB tests, the stress on the specimen, the deformation of Rock specimen and the stress-closure relation of Joint were analyzed. The experimental results show that the JMC and the spatial geometry of Joint surface affect not only the dynamic behavior of Joint but also the stress wave propagation.
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analytical time domain solution of plane wave propagation across a viscoelastic Rock Joint
Rock Mechanics and Rock Engineering, 2017Co-Authors: Jianchun Li, Lyesse Laloui, Jian ZhaoAbstract:The effects of viscoelastic filled Rock Joints on wave propagation are of great significance in Rock engineering. The solutions in time domain for plane longitudinal (P-) and transverse (S-) waves propagation across a viscoelastic Rock Joint are derived based on Maxwell and Kelvin models which are, respectively, applied to describe the viscoelastic deformational behaviour of the Rock Joint and incorporated into the displacement discontinuity model (DDM). The proposed solutions are verified by comparing with the previous studies on harmonic waves, which are simulated by sinusoidal incident P- and S-waves. Comparison between the predicted transmitted waves and the experimental data for P-wave propagation across a Joint filled with clay is conducted. The Maxwell is found to be more appropriate to describe the filled Joint. The parametric studies show that wave propagation is affected by many factors, such as the stiffness and the viscosity of Joints, the incident angle and the duration of incident waves. Furthermore, the dependences of the transmission and reflection coefficients on the specific Joint stiffness and viscosity are different for the Joints with Maxwell and Kelvin behaviours. The alternation of the reflected and transmitted waveforms is discussed, and the application scope of this study is demonstrated by an illustration of the effects of the Joint thickness. The solutions are also extended for multiple parallel Joints with the virtual wave source method and the time-domain recursive method. For an incident wave with arbitrary waveform, it is convenient to adopt the present approach to directly calculate wave propagation across a viscoelastic Rock Joint without additional mathematical methods such as the Fourier and inverse Fourier transforms.
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experimental study of s wave propagation through a filled Rock Joint
Rock Mechanics and Rock Engineering, 2017Co-Authors: Jianchun Li, Haibo Li, Xinping Li, Yun ZhengAbstract:This experimental study proposes a Split Shear Plates model to investigate the effects of a filled Joint on S-wave attenuation. A dynamic impact is used to create frictional slip and generate an incident S-wave. The filled Joint is simulated using a sand layer between two Rock plates. Normal stress is applied to the filled Joint, and semiconductor strain gauges are arranged on the two plates to measure the strain. Verification tests are conducted to validate the reliability of the experimental results. A series of tests is performed to investigate the influence of the normal stress, filled thickness and particle size of the filling materials on the S-wave propagation. The transmission coefficients of the filled Joints are smaller than those of the non-filled Joints because of the attenuation associated with the filling materials. Additionally, the transmission coefficients exhibit a stronger correlation with the normal stress than with the filled thickness or particle size. The transmission coefficients increase at a decreasing rate as normal pressure increases.
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stress wave interaction with a nonlinear and slippery Rock Joint
International Journal of Rock Mechanics and Mining Sciences, 2011Co-Authors: Jianchun Li, Jian ZhaoAbstract:Keywords: Deformational Behavior ; Parallel Fractures ; Single Fractures ; Shear-Strength ; Elastic-Waves ; Transmission ; Propagation ; Attenuation ; Boundary ; Model Reference EPFL-ARTICLE-171633doi:10.1016/j.ijrmms.2010.11.013View record in Web of Science Record created on 2011-12-16, modified on 2016-08-09
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three phase medium model for filled Rock Joint and interaction with stress waves
International Journal for Numerical and Analytical Methods in Geomechanics, 2011Co-Authors: Jianchun Li, Jian ZhaoAbstract:A three-phase medium model is proposed in describing the dynamic property of filled Rock Joints and an analytical study on longitudinal wave transmission normally across a three-phase Rock Joint is presented. Parameters in the three-phase medium model were determined by a series of modified split Hopkinson pressure bar (SHPB) tests, where a sand or clay layer was used to represent an artificially filled Rock Joint. The effect of the unloading path on the transmitted wave was discussed by comparing the analytical and SHPB test results. The derived wave transmission coefficients across the filled Joint agreed very well with those from the test results. Both the analytical and the test results showed that the wave transmission coefficients were affected by the mechanical properties of the fillings. Parametric studies with respect to the volume ratios of water and air in the three-phase medium and the type of filling material have also been performed. Copyright (C) 2010 John Wiley & Sons, Ltd.
Shigui Du - One of the best experts on this subject based on the ideXlab platform.
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Shear Resistance of Rock Joint under Nonuniform Normal Stress
Advances in Materials Science and Engineering, 2020Co-Authors: Hu Wang, Rui Yong, Yifan Chen, Yixian Wang, Shigui DuAbstract:Many factors influence the shear resistance of Rock Joints. Among them, the above overburden load is the most important factor. The uneven thickness of the overburden causes the Joints to be subjected to the nonuniform distribution load. While the peak shear strength shows nonlinear relationship with normal stress, linear superposition cannot be used to calculate the overall shear resistance of Joint under nonuniform normal stress distribution. In this paper, the nonlinear shear strength model, JRC-JCS model, is applied to study the overall shear resistance of the Joint under four nonuniform distribution patterns of normal stress. The results show that when the normal stress is distributed in a nonuniform way, the shear resistance provided by Rock Joint as a whole decreases with the increase of the normal stress distribution interval. Given the nonuniform distribution of normal stress along the Joint, the shear resistance obtained by the Mohr-Coulomb linear model is overestimated. In order to give full play to the overall shear performance of the Joint, the shear strength at different positions on the Joint should be as close as possible. Then, the shear strength of Joint parts can enter peak state condition simultaneously, at which time the shear strength is fully exerted.
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an empirical statistical constitutive relationship for Rock Joint shearing considering scale effect
Comptes Rendus Mecanique, 2019Co-Authors: Rui Yong, Yifan Chen, Shigui DuAbstract:Abstract The scale effect of Rock Joint shearing is of great significance in Rock engineering. Most existing shear constitutive models could describe the pre- and post-peak deformation of Rock Joints, but only in one particular scale, that is, those existing models will fail to depict the Rock Joint shearing in different length scales. Therefore, this study aims to establish a constitutive relationship for Rock Joints with considering the scale effect. Based on the assumption of a random statistical distribution of Rock material strength and statistical mesoscopic damage theory, damage variables are defined as the ratio of the number of damaged elements to the total number in the shear process. Together with the nonlinear relationship between the microelement failure and the Joint scale, an empirical statistical constitutive relationship for Joint is established. And then, the determination method of constitutive relationship parameters and the variation laws with the scale are discussed. Results show that the predicted results of the proposed empirical relationship not only agree well with the experimental results but also fully describe nonlinear deformation, pre-peak softening, post-peak softening, residual stage, and other mechanical properties of the shear deformation of Joint with different dimensions, thereby demonstrating the rationality of the constitutive relationship. The physical meaning of the constitutive relationship parameters is clear, and the expressions of the constitutive relationship parameters can be deduced from the experimental results. In addition, the influence of scale effect on the shear deformation of Rock Joints can be quantified using parameters, which help accurately describe the action form of scale effect.
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expressions of Rock Joint roughness coefficient using neutrosophic interval statistical numbers
viXra, 2017Co-Authors: Jiqian Chen, Shigui Du, Jun Ye, Rui YongAbstract:In nature, the mechanical properties of geological bodies are very complex, and their various mechanical parameters are vague, incomplete, imprecise, and indeterminate. However, we cannot express them by the crisp values in classical probability and statistics.
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expressions of Rock Joint roughness coefficient using neutrosophic interval statistical numbers
Symmetry, 2017Co-Authors: Jiqian Chen, Shigui Du, Jun Ye, Rui YongAbstract:In nature, the mechanical properties of geological bodies are very complex, and their various mechanical parameters are vague, incomplete, imprecise, and indeterminate. However, we cannot express them by the crisp values in classical probability and statistics. In geotechnical engineering, we need to try our best to approximate exact values in indeterminate environments because determining the Joint roughness coefficient (JRC) effectively is a key parameter in the shear strength between Rock Joint surfaces. In this original study, we first propose neutrosophic interval probability (NIP) and define the confidence degree based on the cosine measure between NIP and the ideal NIP. Then, we propose a new neutrosophic interval statistical number (NISN) by combining the neutrosophic number with the confidence degree to express indeterminate statistical information. Finally, we apply NISNs to express JRC under indeterminate (imprecise, incomplete, and uncertain, etc.) environments. By an actual case, the results demonstrate that NISNs are suitable and effective for JRC expressions and have the objective advantage.
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neutrosophic functions of the Joint roughness coefficient and the shear strength a case study from the pyroclastic Rock mass in shaoxing city china
Mathematical Problems in Engineering, 2016Co-Authors: Jun Ye, Rui Yong, Qifeng Liang, Man Huang, Shigui DuAbstract:Many studies have been carried out to investigate the scale effect on the shear behavior of Rock Joints. However, existing methods are difficult to determinate the Joint roughness coefficient (JRC) and the shear strength of Rock Joints with incomplete and indeterminate information; the nature of scale dependency of Rock Joints is still unknown and remains an ongoing debate. Thus, this paper establishes two neutrosophic functions of the JRC values and the shear strength based on neutrosophic theory to express and handle the incomplete and indeterminate problems in the analyses of the JRC and the shear strength. An example, including four Rock Joint samples derived from the pyroclastic Rock mass in Shaoxing city, China, is provided to show the effectiveness and rationality of the developed method. The experimental results demonstrate that the proposed neutrosophic functions can express and deal with the incomplete and indeterminate problems of the test data caused by geometry complexity of the Rock Joint surface and sampling bias. They provide a new approach for estimating the JRC values of the different-sized test profiles and the peak shear strength of Rock Joints.
Rui Yong - One of the best experts on this subject based on the ideXlab platform.
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Shear Resistance of Rock Joint under Nonuniform Normal Stress
Advances in Materials Science and Engineering, 2020Co-Authors: Hu Wang, Rui Yong, Yifan Chen, Yixian Wang, Shigui DuAbstract:Many factors influence the shear resistance of Rock Joints. Among them, the above overburden load is the most important factor. The uneven thickness of the overburden causes the Joints to be subjected to the nonuniform distribution load. While the peak shear strength shows nonlinear relationship with normal stress, linear superposition cannot be used to calculate the overall shear resistance of Joint under nonuniform normal stress distribution. In this paper, the nonlinear shear strength model, JRC-JCS model, is applied to study the overall shear resistance of the Joint under four nonuniform distribution patterns of normal stress. The results show that when the normal stress is distributed in a nonuniform way, the shear resistance provided by Rock Joint as a whole decreases with the increase of the normal stress distribution interval. Given the nonuniform distribution of normal stress along the Joint, the shear resistance obtained by the Mohr-Coulomb linear model is overestimated. In order to give full play to the overall shear performance of the Joint, the shear strength at different positions on the Joint should be as close as possible. Then, the shear strength of Joint parts can enter peak state condition simultaneously, at which time the shear strength is fully exerted.
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an empirical statistical constitutive relationship for Rock Joint shearing considering scale effect
Comptes Rendus Mecanique, 2019Co-Authors: Rui Yong, Yifan Chen, Shigui DuAbstract:Abstract The scale effect of Rock Joint shearing is of great significance in Rock engineering. Most existing shear constitutive models could describe the pre- and post-peak deformation of Rock Joints, but only in one particular scale, that is, those existing models will fail to depict the Rock Joint shearing in different length scales. Therefore, this study aims to establish a constitutive relationship for Rock Joints with considering the scale effect. Based on the assumption of a random statistical distribution of Rock material strength and statistical mesoscopic damage theory, damage variables are defined as the ratio of the number of damaged elements to the total number in the shear process. Together with the nonlinear relationship between the microelement failure and the Joint scale, an empirical statistical constitutive relationship for Joint is established. And then, the determination method of constitutive relationship parameters and the variation laws with the scale are discussed. Results show that the predicted results of the proposed empirical relationship not only agree well with the experimental results but also fully describe nonlinear deformation, pre-peak softening, post-peak softening, residual stage, and other mechanical properties of the shear deformation of Joint with different dimensions, thereby demonstrating the rationality of the constitutive relationship. The physical meaning of the constitutive relationship parameters is clear, and the expressions of the constitutive relationship parameters can be deduced from the experimental results. In addition, the influence of scale effect on the shear deformation of Rock Joints can be quantified using parameters, which help accurately describe the action form of scale effect.
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expressions of Rock Joint roughness coefficient using neutrosophic interval statistical numbers
viXra, 2017Co-Authors: Jiqian Chen, Shigui Du, Jun Ye, Rui YongAbstract:In nature, the mechanical properties of geological bodies are very complex, and their various mechanical parameters are vague, incomplete, imprecise, and indeterminate. However, we cannot express them by the crisp values in classical probability and statistics.
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expressions of Rock Joint roughness coefficient using neutrosophic interval statistical numbers
Symmetry, 2017Co-Authors: Jiqian Chen, Shigui Du, Jun Ye, Rui YongAbstract:In nature, the mechanical properties of geological bodies are very complex, and their various mechanical parameters are vague, incomplete, imprecise, and indeterminate. However, we cannot express them by the crisp values in classical probability and statistics. In geotechnical engineering, we need to try our best to approximate exact values in indeterminate environments because determining the Joint roughness coefficient (JRC) effectively is a key parameter in the shear strength between Rock Joint surfaces. In this original study, we first propose neutrosophic interval probability (NIP) and define the confidence degree based on the cosine measure between NIP and the ideal NIP. Then, we propose a new neutrosophic interval statistical number (NISN) by combining the neutrosophic number with the confidence degree to express indeterminate statistical information. Finally, we apply NISNs to express JRC under indeterminate (imprecise, incomplete, and uncertain, etc.) environments. By an actual case, the results demonstrate that NISNs are suitable and effective for JRC expressions and have the objective advantage.
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neutrosophic functions of the Joint roughness coefficient and the shear strength a case study from the pyroclastic Rock mass in shaoxing city china
Mathematical Problems in Engineering, 2016Co-Authors: Jun Ye, Rui Yong, Qifeng Liang, Man Huang, Shigui DuAbstract:Many studies have been carried out to investigate the scale effect on the shear behavior of Rock Joints. However, existing methods are difficult to determinate the Joint roughness coefficient (JRC) and the shear strength of Rock Joints with incomplete and indeterminate information; the nature of scale dependency of Rock Joints is still unknown and remains an ongoing debate. Thus, this paper establishes two neutrosophic functions of the JRC values and the shear strength based on neutrosophic theory to express and handle the incomplete and indeterminate problems in the analyses of the JRC and the shear strength. An example, including four Rock Joint samples derived from the pyroclastic Rock mass in Shaoxing city, China, is provided to show the effectiveness and rationality of the developed method. The experimental results demonstrate that the proposed neutrosophic functions can express and deal with the incomplete and indeterminate problems of the test data caused by geometry complexity of the Rock Joint surface and sampling bias. They provide a new approach for estimating the JRC values of the different-sized test profiles and the peak shear strength of Rock Joints.
Mountaka Souley - One of the best experts on this subject based on the ideXlab platform.
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Modeling surface roughness degradation of Rock Joint wall during monotonic and cyclic shearing
Acta Geotechnica, 2007Co-Authors: Tikou Belem, Mountaka Souley, Françoise HomandAbstract:Based on previously proposed surface roughness description parameters ( k _a, θ_s, SR_s, DR_r, a _0), two generalized Rock Joint surface roughness degradation models were proposed to predict the variation of Joint surface degradation during shearing under both constant normal stress (CNS) and constant normal stiffness (CNK) loading conditions. The first model was developed based on the evolution of secondary roughness (an extension of an existing model) and the second was developed based on the concept of “average asperity probable contact angle.” Model variables can be initial normal stress (σ_n0; k _n ≥ 0), normal stiffness ( k _n; σ_n0 ≥ 0), accumulated shear displacement u _s-tot (monotonic or cyclic shearing), and surface roughness amplitude a _0. Good agreement between experimental and predicted degradation was observed. The models also allow prediction of surface degradation in large-scale shear fractures. Both models are semi-incremental, readily implemented in a numerical code, and adaptable to existing elastoplastic Joint behavior models.
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Friction and degradation of Rock Joint surfaces under shear loads
International Journal for Numerical and Analytical Methods in Geomechanics, 2001Co-Authors: Françoise Homand, Tikou Belem, Mountaka SouleyAbstract:The morpho-mechanical behaviour of one artificial granite Joint with hammered surfaces, one artificial regularly undulated Joint and one natural schist Joint was studied. The hammered granite Joints underwent 5 cycles of direct shear under 3 normal stress levels ranging between 0.3 and 4 MPa. The regularly undulated Joint underwent 10 cycles of shear under 6 normal stress levels ranging between 0.5 and 5 MPa and the natural schist replicas underwent a monotonics shear under 5 normal stress levels ranging between 0.4 and 2.4 MPa. These direct shear tests were performed using a new computer-controlled 3D-shear apparatus. To characterize the morphology evolution of the sheared Joints, a laser sensor profilometer was used to perform surface data measurements prior to and after each shear test. Based on a new characterization of Joint surface roughness viewed as a combination of primary and secondary roughness and termed by the Joint surface roughness, SRs, one parameter termed ‘Joint surface degradation’, Dw, has been defined to quantify the degradation of the sheared Joints. Examinations of SRs and Dw prior to and after shearing indicate that the hammered surfaces are more damaged than the two other surfaces. The peak strength of hammered Joint with zero-dilatancy, therefore, significantly differs from the classical formulation of dilatant Joint strength. An attempt has been made to model the peak strength of hammered Joint surfaces and dilatant Joints with regard to their surface degradation in the course of shearing and two peak strength criteria are proposed. Input parameters are initial morphology and initial surface roughness. For the hammered surfaces, the degradation mechanism is dominant over the phenomenon of dilatancy, whereas for a dilatant Joint both mechanisms are present. A comparison between the proposed models and the experimental results indicates a relatively good agreement. In particular, compared to the well-known shear strength criteria of Ladanyi and Archambault or Saeb, these classical criteria significantly underestimate and overestimate the observed peak strength, respectively, under low and high normal stress levels. In addition and based on our experimental investigations, we put forward a model to predict the evolution of Joint morphology and the degree of degradation during the course of shearing. Degradations of the artificial undulated Joint and the natural schist Joint enable us to verify the proposed model with a relatively good agreement. Finally, the model of Ladanyi and Archambault dealing with the proportion of total Joint area sheared through asperities, as, once again, tends to underestimate the observed degradation. Copyright © 2001 John Wiley & Sons, Ltd.
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quantitative parameters for Rock Joint surface roughness
Rock Mechanics and Rock Engineering, 2000Co-Authors: Tikou Belem, F Homandetienne, Mountaka SouleyAbstract:Summary The morphologies of two artificial granite Joints (sanded and hammered surfaces), one artificial regularly undulated Joint and one natural schist Joint, were studied. The sanded and hammered granite Joints underwent 5 cycles of direct shear under 3 normal stress levels ranging between 0.3‐4 MPa. The regularly undulated Joint underwent 10 cycles of shear under 6 normal stress levels ranging between 0.5‐5 MPa and the natural schist replicas underwent a monotonous shear under 5 normal stress levels ranging between 0.4‐2.4 MPa. In order to characterize the morphology of the sheared Joints, a laser sensor profilometer was used to perform surface data measurements prior to and after each shear test. Rather than describing the morphology of the Joints from the single profiles, our characterization is based on a simultaneous analysis of all the surface profiles. Roughness was viewed as a combination of a primary roughness and a secondary roughness. The surface angularity was quantified by defining its three-dimensional mean angle, ys, and the parameter Z2s. The surface anisotropy and the secondary roughness were respectively quantified by the degree of apparent anisotropy, ka, and the surface relative roughness coe‰cient, Rs. The surface sinuosity was quantified by the surface tortuosity coe‰cient, Ts. Comparison between the means of the classical linear parameters and those proposed shows that linear parameters underestimate the morphological characteristics of the Joint surfaces. As a result, the proposed bi-dimensional and tri-dimensional parameters better describe the evolution of the Joints initial roughness during the course of shearing.
