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 Sand- and Clay-Photocured-Geomembrane Interface Shear Characteristics Using Direct Shear Test

2021 ◽  
Vol 13 (15) ◽  
pp. 8201
Author(s):  
Lihua Li ◽  
Han Yan ◽  
Henglin Xiao ◽  
Wentao Li ◽  
Zhangshuai Geng
Keyword(s):  
Soil Surface ◽  
Friction Angle ◽  
Direct Shear ◽  
Tensile Crack ◽  
Shear Tests ◽  
Interface Shear ◽  
Direct Shear Tests ◽  
Carbon Black Powder ◽  
Shear Characteristics ◽  
Impermeable Layer

It is well known that geomembranes frequently and easily fail at the seams, which has been a ubiquitous problem in various applications. To avoid the failure of geomembrane at the seams, photocuring was carried out with 1~5% photoinitiator and 2% carbon black powder. This geomembrane can be sprayed and cured on the soil surface. The obtained geomembrane was then used as a barrier, separator, or reinforcement. In this study, the direct shear tests were carried out with the aim to investigate the interfacial characteristics of photocured geomembrane–clay/sand. The results show that a 2% photoinitiator has a significant effect on the impermeable layer for the photocured geomembrane–clay interface. As for the photocured geomembrane–sand interface, it is reasonable to choose a geomembrane made from a 4% photoinitiator at the boundary of the drainage layer and the impermeable layer in the landfill. In the cover system, it is reasonable to choose a 5% photoinitiator geomembrane. Moreover, as for the interface between the photocurable geomembrane and clay/sand, the friction coefficient increases initially and decreases afterward with the increase of normal stress. Furthermore, the friction angle of the interface between photocurable geomembrane and sand is larger than that of the photocurable geomembrane–clay interface. In other words, the interface between photocurable geomembrane and sand has better shear and tensile crack resistance.

Interface Behavior of Sands from Constant Normal Stiffness Direct Shear Tests

2003 ◽  
Vol 26 (3) ◽  
pp. 19513 ◽  
Author(s):  
L David Suits ◽  
TC Sheahan ◽  
D Porcino ◽  
V Fioravante ◽  
VN Ghionna ◽  
...  
Keyword(s):  
Direct Shear ◽  
Shear Tests ◽  
Interface Behavior ◽  
Normal Stiffness ◽  
Direct Shear Tests ◽  
Constant Normal Stiffness

Numerical direct shear tests to model the shear behaviour of rock joints

2013 ◽  
Vol 51 ◽  
pp. 101-115 ◽  
Author(s):  
M. Bahaaddini ◽  
G. Sharrock ◽  
B.K. Hebblewhite
Keyword(s):  
Rock Joints ◽  
Shear Behaviour ◽  
Direct Shear ◽  
Shear Tests ◽  
Direct Shear Tests

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.

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