TY - JOUR
T1 - Numerical study of the mechanical behaviour of unwelded block in matrix rocks under direct shearing
AU - Sheikhpourkhani, Amir Mohammad
AU - Bahaaddini, Mojtaba
AU - Oh, Joung
AU - Masoumi, Hossein
N1 - Funding Information:
The authors would like to acknowledge Mr. Amir Yazdani, Dr. Saeed Karimi Nasab, and Dr. Hossein Jalalifar for kindly providing the results of their physical experiments as well as their invaluable comments.
Publisher Copyright:
© 2023, Springer-Verlag GmbH Germany, part of Springer Nature.
PY - 2024
Y1 - 2024
N2 - Block in matrix rocks (bimrocks) are known as a challenging material for engineering geologists due to their complex composition and associated difficulties in the determination of their mechanical properties. A novel numerical approach has been developed for the simulation of unwelded bimrocks based on the discrete element method. Three different types of contacts, including matrix–matrix, matrix-block and block-block, were assigned to the particles to mimic the mechanical behaviour of unwelded bimrocks. To investigate the validity of numerical models, the uniaxial compression and direct shear tests under different normal stresses were simulated and their results were compared with the physical experiments (glass bead blocks cemented by matrix plaster). The numerical uniaxial compressive strength (UCS) and direct shear tests at low volumetric block proportion (VBP) were found to be in good agreement with the experimental data, while they diverged with an increase in both VBP and the applied normal stress. It was found that an increase in VBP can lead to a decrease in both UCS and cohesive strength while the frictional strength increases. Also, it was concluded that an increase in the failed block-matrix contacts can lead to a decrease in the cohesion and UCS. At the same time, the occlusion effect of blocks can increase the internal friction angle. Detailed analysis on cracking mechanism showed that the increase in VBP results in a decrease in both crack initiation and damage stresses. Sensitivity analysis on micro-parameters showed that the tensile strength of block-matrix contacts is the most effective parameter on the strength.
AB - Block in matrix rocks (bimrocks) are known as a challenging material for engineering geologists due to their complex composition and associated difficulties in the determination of their mechanical properties. A novel numerical approach has been developed for the simulation of unwelded bimrocks based on the discrete element method. Three different types of contacts, including matrix–matrix, matrix-block and block-block, were assigned to the particles to mimic the mechanical behaviour of unwelded bimrocks. To investigate the validity of numerical models, the uniaxial compression and direct shear tests under different normal stresses were simulated and their results were compared with the physical experiments (glass bead blocks cemented by matrix plaster). The numerical uniaxial compressive strength (UCS) and direct shear tests at low volumetric block proportion (VBP) were found to be in good agreement with the experimental data, while they diverged with an increase in both VBP and the applied normal stress. It was found that an increase in VBP can lead to a decrease in both UCS and cohesive strength while the frictional strength increases. Also, it was concluded that an increase in the failed block-matrix contacts can lead to a decrease in the cohesion and UCS. At the same time, the occlusion effect of blocks can increase the internal friction angle. Detailed analysis on cracking mechanism showed that the increase in VBP results in a decrease in both crack initiation and damage stresses. Sensitivity analysis on micro-parameters showed that the tensile strength of block-matrix contacts is the most effective parameter on the strength.
KW - Bimrocks
KW - Bonded particle model
KW - Direct shear test
KW - Discrete element method
KW - Numerical modelling
KW - Volumetric block proportion (VBP)
UR - http://www.scopus.com/inward/record.url?scp=85180550153&partnerID=8YFLogxK
U2 - 10.1007/s10064-023-03507-7
DO - 10.1007/s10064-023-03507-7
M3 - Article
AN - SCOPUS:85180550153
SN - 1435-9529
VL - 83
JO - Bulletin of Engineering Geology and the Environment
JF - Bulletin of Engineering Geology and the Environment
IS - 1
M1 - 22
ER -