Influence of asperity morphology on failure characteristics and shear strength properties of rock joints under direct shear tests

Xiaobo Zhang, Qinghui Jiang, Pinnaduwa Kulatilake, Feng Xiong, Chi Yao, Zhicheng Tang

Research output: Contribution to journalArticle

Abstract

The asperitymorphology has profound influences on the failure characteristics and shear strength of rock joints. To investigate these influences, degradation characteristics and mechanical properties were studied based on direct shear tests conducted on six groups of artificial rock joints with regular profiles. For each group of joints, the joint profile consisted of several asperities with a particular amplitude and inclination angle. After completion of shear tests, the degradation of asperities was analyzed and interpreted by the following four types of failure modes: frictional sliding, incomplete shear-off, complete shear-off, and tensile cutoff. The results revealed that in addition to the applied normal stress, both the amplitude and inclination angle had an important influence on the occurrence of the failure modes. Experimental results showed that the peak shear displacements of all joints were far less than the base length of asperities, and the peak shear displacement rate had a mean of 2.04%, indicating that the peak shear strength wasmobilized at a very small shear displacement. The peak shear strength and peak friction angle were found to increase with increasing inclination angle in a moderate range up to a certain angle due to sliding and shear failure mechanisms. With further increase of the inclination angle, the asperities tended to failure under tensile mode and resulted in a decreasing trend of both the shear strength and peak friction angle. Experimental results showed that the amplitude had a positive correlation with the strength of rock joints. An existing theoretical model was extended to explain the mechanism behind the aforementioned phenomena observed through laboratory experiments. The results of this study are beneficial for understanding the shear mechanism and the importance of considering both the inclination angle and amplitude in the mechanical behavior of rock joints.

Original languageEnglish (US)
Article number04018196
JournalInternational Journal of Geomechanics
Volume19
Issue number2
DOIs
StatePublished - Feb 1 2019

Fingerprint

asperity
shear strength
shear test
shear stress
rocks
rock
testing
sliding
friction
failure mechanism
degradation
mechanical property
strength (mechanics)
mechanical properties

Keywords

  • Asperity amplitude
  • Asperity inclination angle
  • Degradation
  • Failure modes
  • Rock joints
  • Shear strength

ASJC Scopus subject areas

  • Soil Science

Cite this

Influence of asperity morphology on failure characteristics and shear strength properties of rock joints under direct shear tests. / Zhang, Xiaobo; Jiang, Qinghui; Kulatilake, Pinnaduwa; Xiong, Feng; Yao, Chi; Tang, Zhicheng.

In: International Journal of Geomechanics, Vol. 19, No. 2, 04018196, 01.02.2019.

Research output: Contribution to journalArticle

@article{8389a1eae93f430197d9a672d9baff5e,
title = "Influence of asperity morphology on failure characteristics and shear strength properties of rock joints under direct shear tests",
abstract = "The asperitymorphology has profound influences on the failure characteristics and shear strength of rock joints. To investigate these influences, degradation characteristics and mechanical properties were studied based on direct shear tests conducted on six groups of artificial rock joints with regular profiles. For each group of joints, the joint profile consisted of several asperities with a particular amplitude and inclination angle. After completion of shear tests, the degradation of asperities was analyzed and interpreted by the following four types of failure modes: frictional sliding, incomplete shear-off, complete shear-off, and tensile cutoff. The results revealed that in addition to the applied normal stress, both the amplitude and inclination angle had an important influence on the occurrence of the failure modes. Experimental results showed that the peak shear displacements of all joints were far less than the base length of asperities, and the peak shear displacement rate had a mean of 2.04{\%}, indicating that the peak shear strength wasmobilized at a very small shear displacement. The peak shear strength and peak friction angle were found to increase with increasing inclination angle in a moderate range up to a certain angle due to sliding and shear failure mechanisms. With further increase of the inclination angle, the asperities tended to failure under tensile mode and resulted in a decreasing trend of both the shear strength and peak friction angle. Experimental results showed that the amplitude had a positive correlation with the strength of rock joints. An existing theoretical model was extended to explain the mechanism behind the aforementioned phenomena observed through laboratory experiments. The results of this study are beneficial for understanding the shear mechanism and the importance of considering both the inclination angle and amplitude in the mechanical behavior of rock joints.",
keywords = "Asperity amplitude, Asperity inclination angle, Degradation, Failure modes, Rock joints, Shear strength",
author = "Xiaobo Zhang and Qinghui Jiang and Pinnaduwa Kulatilake and Feng Xiong and Chi Yao and Zhicheng Tang",
year = "2019",
month = "2",
day = "1",
doi = "10.1061/(ASCE)GM.1943-5622.0001347",
language = "English (US)",
volume = "19",
journal = "International Journal of Geomechanics",
issn = "1532-3641",
publisher = "American Society of Civil Engineers (ASCE)",
number = "2",

}

TY - JOUR

T1 - Influence of asperity morphology on failure characteristics and shear strength properties of rock joints under direct shear tests

AU - Zhang, Xiaobo

AU - Jiang, Qinghui

AU - Kulatilake, Pinnaduwa

AU - Xiong, Feng

AU - Yao, Chi

AU - Tang, Zhicheng

PY - 2019/2/1

Y1 - 2019/2/1

N2 - The asperitymorphology has profound influences on the failure characteristics and shear strength of rock joints. To investigate these influences, degradation characteristics and mechanical properties were studied based on direct shear tests conducted on six groups of artificial rock joints with regular profiles. For each group of joints, the joint profile consisted of several asperities with a particular amplitude and inclination angle. After completion of shear tests, the degradation of asperities was analyzed and interpreted by the following four types of failure modes: frictional sliding, incomplete shear-off, complete shear-off, and tensile cutoff. The results revealed that in addition to the applied normal stress, both the amplitude and inclination angle had an important influence on the occurrence of the failure modes. Experimental results showed that the peak shear displacements of all joints were far less than the base length of asperities, and the peak shear displacement rate had a mean of 2.04%, indicating that the peak shear strength wasmobilized at a very small shear displacement. The peak shear strength and peak friction angle were found to increase with increasing inclination angle in a moderate range up to a certain angle due to sliding and shear failure mechanisms. With further increase of the inclination angle, the asperities tended to failure under tensile mode and resulted in a decreasing trend of both the shear strength and peak friction angle. Experimental results showed that the amplitude had a positive correlation with the strength of rock joints. An existing theoretical model was extended to explain the mechanism behind the aforementioned phenomena observed through laboratory experiments. The results of this study are beneficial for understanding the shear mechanism and the importance of considering both the inclination angle and amplitude in the mechanical behavior of rock joints.

AB - The asperitymorphology has profound influences on the failure characteristics and shear strength of rock joints. To investigate these influences, degradation characteristics and mechanical properties were studied based on direct shear tests conducted on six groups of artificial rock joints with regular profiles. For each group of joints, the joint profile consisted of several asperities with a particular amplitude and inclination angle. After completion of shear tests, the degradation of asperities was analyzed and interpreted by the following four types of failure modes: frictional sliding, incomplete shear-off, complete shear-off, and tensile cutoff. The results revealed that in addition to the applied normal stress, both the amplitude and inclination angle had an important influence on the occurrence of the failure modes. Experimental results showed that the peak shear displacements of all joints were far less than the base length of asperities, and the peak shear displacement rate had a mean of 2.04%, indicating that the peak shear strength wasmobilized at a very small shear displacement. The peak shear strength and peak friction angle were found to increase with increasing inclination angle in a moderate range up to a certain angle due to sliding and shear failure mechanisms. With further increase of the inclination angle, the asperities tended to failure under tensile mode and resulted in a decreasing trend of both the shear strength and peak friction angle. Experimental results showed that the amplitude had a positive correlation with the strength of rock joints. An existing theoretical model was extended to explain the mechanism behind the aforementioned phenomena observed through laboratory experiments. The results of this study are beneficial for understanding the shear mechanism and the importance of considering both the inclination angle and amplitude in the mechanical behavior of rock joints.

KW - Asperity amplitude

KW - Asperity inclination angle

KW - Degradation

KW - Failure modes

KW - Rock joints

KW - Shear strength

UR - http://www.scopus.com/inward/record.url?scp=85058221766&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85058221766&partnerID=8YFLogxK

U2 - 10.1061/(ASCE)GM.1943-5622.0001347

DO - 10.1061/(ASCE)GM.1943-5622.0001347

M3 - Article

VL - 19

JO - International Journal of Geomechanics

JF - International Journal of Geomechanics

SN - 1532-3641

IS - 2

M1 - 04018196

ER -