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Advances in Concrete Construction
  Volume 13, Number 1, January 2022 , pages 83-99
DOI: https://doi.org/10.12989/acc.2022.13.1.083
 


The comparison between NBD test results and SCB test results using experimental test and numerical simulation
Jinwei Fu, Vahab Sarfarazi, Hadi Haeri, K. Naderi, Mohammad Fatehi Marji and Mengdi Guo

 
Abstract
    The two, NBD and SCB tests using gypsum circular discs each containing a single notch have been experimentally accomplished in a rock mechanics laboratory. These specimens have also been numerically modelled by a two-dimensional particle flow which is based on Discrete Element Method (DEM). Each testing specimen had a thickness of 5 cm with 10 cm in diameter. The specimens' lengths varied as 2, 3, and 4 cm; and the specimens' notch angles varied as 0o, 45o and 90o. Similar semi-circular gypsum specimens were also prepared each contained one edge notch with angles 0o or 45o. The uniaxial testing machine was used to perform the experimental tests for both NBD and SCB gypsum specimens. At the same time, the numerical simulation of these tests were performed by PFC2D. The experimental results showed that the failure mechanism of rocks is mainly affected by the orientations of joints with respect to the loading directions. The failure mechanism and fracturing patterns of the gypsum specimens are directly related to the final failure loading. It has been shown that the number of induced tensile cracks showing the specimens' tensile behavior, and increases by decreasing the length and angle of joints. It should be noted that the fracture toughness of rocks' specimens obtained by NBD tests was higher than that of the SCB tests. The fracture toughness of rocks usually increases with the increasing of joints' angles but increasing the joints' lengths do not change the fracture toughness. The numerical solutions and the experimental results for both NDB and SCB tests give nearly similar fracture patterns during the loading process.
 
Key Words
    crack propagation patterns; discrete element method; fracture toughness; NBD and SCB tests
 
Address
Jinwei Fu: School of Civil Engineering and Transportation, North China University of Water Resources and Electric Power, Zhengzhou, 450046, China
Vahab Sarfarazi: Department of Mining Engineering, Hamedan University of Technology, Hamedan, Iran
Hadi Haeri: State Key Laboratory for Deep Geomechanics and Underground Engineering, Beijing, 100083, China
K. Naderi: State Key Laboratory for Deep Geomechanics and Underground Engineering, Beijing, 100083, China
Mohammad Fatehi Marji: Head of Mine Exploitation Engineering Department, Faculty of Mining and Metallurgy, Institution of Engineering, Yazd University, Yazd, Iran
Mengdi Guo: School of Civil Engineering and Transportation, North China University of Water Resources and Electric Power, Zhengzhou, 450046, China
 
References
    -acc1301007-
 

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