scholarly journals Research Progress on Shear Characteristics of Rock Joints under Constant Normal Stiffness Boundary Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Guansheng Han ◽  
Fei Xiong ◽  
Yu Zhou ◽  
Leibo Song ◽  
Xingkai Wang
Keyword(s):  
Boundary Conditions ◽  
Rock Joint ◽  
Test System ◽  
Rock Joints ◽  
Research Progress ◽  
Shear Tests ◽  
Underground Engineering ◽  
Normal Stiffness ◽  
Shear Characteristics ◽  
Constant Normal Stiffness

The constant normal stiffness (CNS) boundary condition is more representative for the underground engineering, in which the shear-induced dilation is restricted by surrounding rocks, resulting in an increase in the normal stress. Therefore, the use of CNS boundary conditions in the research of shear-slip failure of underground rock engineering is more in line with the actual situation. Taking the instability and failure of surrounding rock in underground engineering as the background, the present study introduces the engineering background of CNS boundary conditions and the research progress on shear characteristics of rock joints under CNS boundary conditions. Three key directions for future research are proposed based on the latest research results of shear characteristics of rock joint under CNS boundary conditions: ① developing a rock joint shear test system that can realize the function of “CNS boundary conditions + shear-seepage test + visualization”; ② carrying out the shear tests of real rock joints under CNS boundary conditions based on 3D scanning and 3D carving technology; and ③ carrying out the shear tests of rock joint network under CNS boundary conditions.

scholarly journals Simulation of direct shear tests using a forces on fracture surfaces (FFS) approach

2021 ◽  
Vol 80 (8) ◽  
Author(s):  
Thomas Frühwirt ◽  
Daniel Pötschke ◽  
Heinz Konietzky
Keyword(s):  
Normal Load ◽  
Crystalline Rock ◽  
Rock Joints ◽  
Direct Shear ◽  
Shear Tests ◽  
Data Set ◽  
Direct Shear Tests ◽  
Complex Process ◽  
Shear Characteristics ◽  
Constant Normal Stiffness

AbstractThe aim of this work is to provide a complete data set of direct shear tests and to propose a corresponding simulation approach. Tests have been conducted on crystalline rock samples applying constant normal load (CNL) and constant normal stiffness (CNS) boundary conditions. A physical consistent algorithm which explicitly calculates the forces acting on the fracture surface (FFS) has been developed. This FFS approach can explain the occurrence of surface degradation and shows the main shear characteristics. After all, shearing of rough rock joints remains a complex process and the differences between laboratory and simulation results are still significant in some cases. All data and input files are provided free for download and testing.

scholarly journals Numerical Analysis Method of Shear Properties of Infilled Joints under Constant Normal Stiffness Condition

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Xiangyu Wang ◽  
Ruofan Wang ◽  
Zizheng Zhang
Keyword(s):  
Numerical Analysis ◽  
Normal Stress ◽  
Shear Failure ◽  
Rock Joints ◽  
Analysis Method ◽  
Shear Properties ◽  
Normal Stiffness ◽  
Numerical Analysis Method ◽  
Constant Normal Stiffness ◽  
Good Agreement

The direct shear test is implemented in this paper for infilled joints under constant normal stiffness (CNS) condition with the finite difference software FLAC3D. The CNS condition was performed based on a servoprogram developed by FISH language. The effects of initial normal stress, undulating angle, and infilled ratio on the shear failure mode of infilled joints under CNS are revealed based on numerical simulation. It is found that the shear strength of infilled joints will grow along with the increase of the undulating angle and the decrease of the infilled ratio. The numerical analysis method is also able to quantify the effect of multiple factors (initial normal stress and infilled ratio) on shear properties of infilled joints. The model shows a good agreement with the experimental results available in the literatures. Therefore, this study proposed and verified a numerical analysis method capable of studying the effects of normal stress, undulating angles, and infilled ratio on the shear behavior of infilled rock joints.

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