Research on the mechanism and performance of free-surface rock breakage by a disc cutter

Jiang, Haifeng; Zhang, Xiaodi; Liu, Songyong; Cai, Zhenghao

doi:10.1016/j.engfracmech.2022.108336

“…When D/H is smaller than the critical threshold, the side-free face can help improve the rock-breaking efficiency. The critical thresholds of D/H for the studies by Innaurato et al [10], Xu et al [17], Xia et al [15], Geng et al [14], and Jiang et al [12] are 2.5, 1.0, 0.5, 1.2, and 0.5, respectively. This value is affected by the rock type and cutter geometry.…”

Section: Discussion Considering Previous Studiesmentioning

confidence: 89%

“…Ramezanzadeh et al [11] reported a multi-arm type and a reaming type undercutting roadheader that disc cutters break rock under free-face conditions. Based on these machines, Jiang et al [12] simulated the rock-breaking process of a disc cutter under side free face and pre-slotting conditions. The results proved that the free-face-assisted methods provide a potential approach for efficiently breaking hard and extremely hard rock.…”

Section: Introductionmentioning

confidence: 99%

Investigation on the Rock-Fragmentation Process of Conical-Shaped TBM Cutterhead in Extremely Hard Rock Ground

Chen,

Jin,

Hu

et al. 2023

CEJ

0

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Conical-shaped cutterhead is one type of tunnel boring machine (TBM) cutterhead which may have advantage of high rock-breaking efficiency in extremely hard rock ground. This study investigated the rock-fragmentation process of disc cutters on the conical-shaped cutterhead via a series of numerical simulations that had been verified by laboratory rock-fragmentation tests. Firstly, the rock-fragmentation numerical model of the six cutters in the 'flat-cone' contiguous part was built based on cutting mode analysis of the conical-shape cutterhead. The rock sample in the numerical model was synthesized using a grain-based discrete element method (GB-DEM) and the reliability of this approach was verified via scaled rock-fragmentation tests conducted on a self-developed linear cutting machine (LCM). Then, a series of numerical simulations were conducted to study the influence of cutterhead cone angle, cutter spacing, and cutter installation angle on the rock-fragmentation performance. The results were as follows: 1) the nature of rock fragmentation in the cone area is the rock fragmentation under side free-face condition; 2) the penetration specific energy can be reduced and thus the rock-fragmentation efficiency can be improved by appropriately increasing the conical angle, reducing the cutter spacing, and increasing the cutter installation angle; 3) for the studied granite, the optimal conical angle is 25°, the cutter spacing is suggested to be no more than 70 mm, and the cutter tilt angle is suggested to be no more than 3°. The results obtained in this paper can be used as guidance for the design of the conical-shaped cutterhead.

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“…In addition, the mechanism of disc cutter on cutting rock under undercutting mode is different with that under TBM. A disc cutter based on undercutting method, the rock failure mode can change from compression or shear failure to tension failure dominance, which is conducive for crack propagation, causing lower specific energy, and applied in the Wirth Continuous Mining Machine 10 .…”

Section: Introductionmentioning

confidence: 99%

The Mechanism and Performance of Rock Breakage by Undercutting Disc Cutter with Advanced Slotting

Jiang

¹

,

Zhang

²

,

Zhao

³

et al. 2023

Preprint

0

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To study the mechanism and performance of rock breakage by an undercutting disc cutter with advanced slotting, a three-dimensional numerical model of rock cutting by a disc cutter with advanced slotting assistance was established based on the discrete element method. The parallel bond constitutive model was selected to describe the micromechanical properties of rock. The correctness of the established numerical model is verified through rock breakage experiments, and the rock cutting process by the disc cutter was analyzed by a combination of the force chain and crack distribution. The influencing factors, such as advanced slotting depth, cutting thickness, rock strength, and cutter rotation speed, on rock cutting performance were investigated. The results show that a compact zone is gradually formed between the rock and disc cutter at the beginning, then a large number of microscopic tensile and shear cracks in the compact zone due to micro failure of rock are formed; the subsequent main rock fragment is mainly caused by tensile failure; advanced slotting can reduce the rock bearing capacity and bending resistance, the rock above the advanced slotting fractured easily due to its lower bending resistance, and the volume compact zone is relatively small. When the advanced slotting depth is equal to 12.5 mm, the propulsive force and specific energy consumption of rock cutting by the disc cutter are reduced by 61.6% and 16.5%, respectively. The propulsive force and specific energy consumption increase as the rock strength increases, but they tend to close when the rock strength is greater than 80 MPa, which indicates that advanced slotting assistance is more suitable for hard rock.

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“…Moxham 12 compared the rock cutting performance of disc cutter working in the undercutting mode with the conventional rock cutting mode, and proved that the crack is more likely to propagate induced by the free face and forming the larger fragments. Jiang et al 13 believed that the rock failure mode can change from compression or shear failure to tension failure dominance, which is conducive for crack propagation, causing lower specific energy. Moreover, the research on the effect of the structure and cutting parameters of the undercutting disc cutter on the rock breaking performance has also been carried out by the scholars.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, on the basis of the undercutting method with disc cutter, the author proposed the integration of advanced slotting technology into the disc cutter cutting rock as shown in Fig. 1 13 , 22 . By slotting the rocks on the cutting path of the under cutting disc cutter in advance, the difficulty of the disc cutter wedging into hard rock is reduced so that the disc cutter can make full use of the non-tensile property of the rock to wedge the hard rock and reduce the difficulty and load of the disc cutter cutting hard rock.…”

Section: Introductionmentioning

confidence: 99%

The mechanism and performance of rock breakage by undercutting disc cutter with advanced slotting

Jiang

¹

,

Zhang

²

,

Zhao

³

et al. 2023

Sci Rep

Self Cite

1

0

View full text Add to dashboard Cite

To study the mechanism and performance of rock breakage by an undercutting disc cutter with advanced slotting, a three-dimensional numerical model of rock cutting by a disc cutter with advanced slotting assistance was established based on the discrete element method. The parallel bond constitutive model was selected to describe the micromechanical properties of rock. The correctness of the established numerical model is verified through rock breakage experiments, and the rock cutting process by the disc cutter was analyzed by a combination of the force chain and crack distribution. The influencing factors, such as advanced slotting depth, cutting thickness, rock strength, and cutter rotation speed, on rock cutting performance were investigated. The results show that a compact zone is gradually formed between the rock and disc cutter at the beginning, then a large number of microscopic tensile and shear cracks in the compact zone due to micro failure of rock are formed; the subsequent main rock fragment is mainly caused by tensile failure; advanced slotting can reduce the rock bearing capacity and bending resistance, the rock above the advanced slotting fractured easily due to its lower bending resistance, and the volume compact zone is relatively small. When the advanced slotting depth is equal to 12.5 mm, the propulsive force and specific energy consumption of rock cutting by the disc cutter are reduced by 61.6% and 16.5%, respectively. The propulsive force and specific energy consumption increase as the rock strength increases, but they tend to close when the rock strength is greater than 80 MPa, which indicates that advanced slotting assistance is more suitable for hard rock. The results obtained in this paper can provide the operating parameters determination under different factors to some extent of the undercutting disc cutter in a pre-cut condition, which further improve the rock breaking performance of mechanized cutter.

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Research on the mechanism and performance of free-surface rock breakage by a disc cutter

Cited by 20 publications

References 38 publications

Investigation on the Rock-Fragmentation Process of Conical-Shaped TBM Cutterhead in Extremely Hard Rock Ground

Investigation on the Rock-Fragmentation Process of Conical-Shaped TBM Cutterhead in Extremely Hard Rock Ground

The Mechanism and Performance of Rock Breakage by Undercutting Disc Cutter with Advanced Slotting

The mechanism and performance of rock breakage by undercutting disc cutter with advanced slotting

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