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- Lin, Qibin, et al.
(författare)
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Crack coalescence in rock-like specimens with two dissimilar layers and pre-existing double parallel joints under uniaxial compression
- 2021
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Ingår i: International Journal of Rock Mechanics And Mining Sciences. - : Elsevier. - 1365-1609 .- 1873-4545. ; 139
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Tidskriftsartikel (refereegranskat)abstract
- Layered rock masses with joints are widely found in nature. Their mechanical behavior plays a key role in rock engineering applications. However, previous studies have concentrated on the single lithologic layer, and few studies have reported the crack coalescence mechanism in layered rock masses with joints. In this study, uniaxial compression tests were performed on jointed rock-like specimens with two dissimilar layers. The acoustic emission (AE) and the digital image correlation (DIC) techniques are employed to investigate the crack coalescence process of specimens with two dissimilar layers. The influence of the joint angle and rock bridge angle on the mechanical behavior and failure processes in layered rock masses is investigated. The results show that the peak strength is associated with the joint angle and the rock bridge angle. Seven types of crack coalescence have been identified in the specimens, which are not only related to the joint angle and the rock bridge angle but also influenced by the rock layers. Cracks easily coalesce when the joint angle and the rock bridge angle are small. However, when the joint angle and the rock bridge angle are larger, it is difficult for cracks to initiate and propagate in the layer with higher strength. The failure mechanism of the specimens is primarily caused by crack propagation in the layer with lower strength.
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| 2. |
- Lin, Qibin, et al.
(författare)
-
Strength and failure characteristics of jointed rock mass with double circular holes under uniaxial compression : Insights from discrete element method modelling
- 2020
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Ingår i: Theoretical and applied fracture mechanics (Print). - : Elsevier. - 0167-8442 .- 1872-7638. ; 109
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Tidskriftsartikel (refereegranskat)abstract
- Underground projects are typically performed in nonpersistent jointed rock masses. Excavation of tunnels or chambers causes crack initiation, propagation and coalescence, resulting in the instability and destruction of surrounding rocks. The failure behaviour of rocks is complicated owing to the interaction between holes and joints. Therefore, understanding the failure characteristics of holes in jointed rock masses is essential. In this paper, the mechanical characteristics of a jointed rock mass with double circular holes under uniaxial loading was investigated using the discrete element method. The effects of different joint parameters on the strength and failure behaviour of the jointed rock mass with double circular holes were studied. The results show that the existence of joints degrades the mechanical behaviour of the rock mass. Specifically, the peak strength and elastic modulus of the specimens show a “U” shape change with the joint dip angle and reach the minimum value when the angle is 30°. With an increase in joint spacing, the peak strength and elastic modulus increase gradually. An investigation of the crack coalescence process and displacement field of the specimens reveal the crack propagation mechanism based on the interaction between holes and joints under uniaxial loading. Five types of crack coalescence among the holes and adjacent joints were summarized. Four typical failure modes were observed: tensile failure across joints, block rotation failure around holes, shear failure through joint planes and tensile–shear mixed failure through holes.
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