Numerical simulation of pressure relief stress distribution of diamond beaded rope saw cutting in low permeability coal seam
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2023-09-01 |
| Journal | Geomechanics and Geophysics for Geo-Energy and Geo-Resources |
| Authors | Wang We, Xiaochuan Wang, H. Q. Li, Jincheng Hu, Tianyi Zhang |
| Institutions | Wuhan University |
| Citations | 2 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Diamond Beaded Rope Saw Cutting in Low Permeability Coal Seams
Section titled âTechnical Documentation & Analysis: Diamond Beaded Rope Saw Cutting in Low Permeability Coal SeamsâExecutive Summary
Section titled âExecutive SummaryâThis research utilizes finite element modeling (ABAQUS) and the Coulomb friction contact model to analyze the stress distribution resulting from diamond beaded rope saw cutting in low permeability coal seams, confirming the superior efficiency of this method for pressure relief and permeability enhancement.
- Core Mechanism: Pressure relief is primarily driven by tangential slip (shear displacement) of the coal body along the extremely narrow diamond-cut slit surface, contrasting sharply with the normal displacement mechanism of wide hydraulic slots.
- Optimal Geometry: The maximum pressure relief range and amplitude exhibit a âsingle peakâ distribution, achieving maximum effectiveness when the angle (α) between the slit and the maximum in-situ stress is 45°.
- Material Requirement: The effectiveness hinges on the ability of the diamond saw to create an extremely thin, continuous slit, requiring highly durable and precise diamond cutting elements.
- Key Parameter Influence: Increasing slit length and working face length positively correlate with the pressure relief range. A smoother cutting surface (lower friction coefficient, ”) significantly enhances the pressure relief amplitude (up to 82% relief at ”=0.00).
- 6CCVD Value Proposition: 6CCVD provides the high-performance MPCVD Polycrystalline Diamond (PCD) and Single Crystal Diamond (SCD) materials necessary to manufacture the durable, high-precision diamond beads required for this advanced mining technology.
Technical Specifications
Section titled âTechnical SpecificationsâThe following parameters were extracted from the numerical simulation model used to characterize the large-scale coal and surrounding rock behavior.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Model Size (Cube) | 500 x 500 x 500 | m | Large-scale simulation volume |
| Coal Seam Thickness | 4 | m | No. 5 Coal |
| Coal Youngâs Modulus (E) | 1.49 | GPa | Material property (Mohr Coulomb model) |
| Coal Poissonâs Ratio (v) | 0.38 | - | Material property |
| Coal Cohesion (c) | 1.20 | MPa | Material property |
| Coal Internal Friction Angle (Ï) | 20 | ° | Material property |
| Ground Stress (ÏH) | 10 | MPa | Applied three-dimensional ground stress |
| Optimal Slit Angle (α) | 45 | ° | Angle for maximum pressure relief |
| Maximum Pressure Relief Amplitude | Up to 50 | % | Achieved at α=45° (for ÎÏ=5 MPa, ”=0) |
| Slit Length (dl) Range Tested | 150 to 225 | m | Parameter varied in simulation |
| Friction Coefficient (”) Range Tested | 0.00 to 0.13 | - | Parameter varied (lower ” improves relief) |
| In-situ Stress Difference (ÎÏ) Range | 1 to 13 | MPa | Dynamic source of relative dislocation |
Key Methodologies
Section titled âKey MethodologiesâThe study employed a numerical simulation approach based on continuum mechanics and contact surface theory to model the large-scale stress redistribution.
- Modeling Platform: Finite Element Method (FEM) simulation conducted using ABAQUS software.
- Material Model: All coal and surrounding rock materials were characterized using the Mohr Coulomb constitutive model.
- Crack Representation: The diamond beaded slit was modeled as a contact surface with negligible spacing (a crack), rather than a wide hole structure, to accurately capture large-scale rock mass displacement.
- Contact Physics: The Coulomb friction model was adopted to characterize the contact properties and tangential slip behavior between the coal/rock surfaces on both sides of the slit.
- Critical Shear Stress (Ïcrit) defined by: Ïcrit = ”Fn (where Fn is normal pressure and ” is the friction coefficient).
- Iterative Solution: An iterative calculation process based on the principle of stress superposition was used to solve the complex stress distribution problem across partitioned half-planes (Fig. 7).
- Parameter Variation: The simulation systematically varied five key parameters to determine their influence on stress distribution: Slit length (dl), Working face length (ds), Slit angle (α), Seam surface friction coefficient (”), and In-situ stress difference (ÎÏ).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe research confirms that diamond beaded rope saw cutting is a high-efficiency method for geomechanical stress relief, relying on the diamond materialâs ability to create an extremely narrow, durable cut in hard coal and rock. 6CCVD is uniquely positioned to supply the advanced diamond materials required to manufacture these high-performance cutting beads.
Applicable Materials
Section titled âApplicable MaterialsâThe success of this technology depends on the extreme hardness and wear resistance of the diamond beads. 6CCVD recommends the following materials for manufacturing the cutting elements:
| 6CCVD Material | Recommended Grade | Application Relevance |
|---|---|---|
| Polycrystalline Diamond (PCD) | Mining/Abrasive Grade PCD | Ideal for rope saw beads due to exceptional toughness, high wear resistance, and thermal stability required for cutting hard, abrasive coal and rock masses. |
| Single Crystal Diamond (SCD) | High-Durability SCD | Suitable for specialized cutting segments where maximum precision and edge retention are critical, potentially used in the initial cutting tool or guide elements. |
| Boron-Doped Diamond (BDD) | Not Applicable | BDD is primarily for electrochemical or sensor applications, not mechanical cutting. |
Customization Potential
Section titled âCustomization PotentialâThe paper highlights that optimizing the cutting process involves minimizing the friction coefficient (”) and maximizing cutting speed and bead density (Conclusion 5). 6CCVD supports manufacturers in achieving these goals through custom material engineering:
- Custom Dimensions: We supply PCD plates and wafers up to 125mm in custom geometries, suitable for laser cutting or sintering into specific bead shapes and sizes required for optimal rope saw design.
- Precision Thickness: We offer SCD and PCD materials with thicknesses ranging from 0.1”m to 500”m, ensuring the material integrity needed for durable cutting segments.
- Advanced Metalization: Diamond beads require robust bonding to the wire rope. 6CCVD offers in-house metalization services (including Ti, W, and Cu) critical for enhancing the adhesion and thermal management of the diamond segments during the sintering process.
- Ultra-Low Roughness Polishing: While the final bead surface is rough, 6CCVD can provide highly polished diamond substrates (Ra < 5nm for inch-size PCD) for tooling or calibration purposes, ensuring the highest quality starting material.
Engineering Support
Section titled âEngineering SupportâThe simulation results emphasize the importance of selecting optimal fracture and geological parameters (e.g., the 45° angle, low friction). 6CCVDâs in-house PhD team specializes in diamond material science and can provide expert consultation to rope saw manufacturers and mining engineers:
- Material Selection Optimization: Assistance in selecting the optimal diamond grade (PCD grain size, density, and binder composition) to maximize wear life and minimize the effective friction coefficient (”) during the cutting of specific coal/rock types.
- Application Extension: Support for extending this pressure relief technology to other hard rock or low-permeability geological formations requiring precision slotting.
Call to Action: For custom specifications or material consultation regarding high-performance diamond cutting elements for geomechanical applications, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Abstract The diamond bead slit is a practical method for changing the stress distribution of low permeability coal seam and achieving pressure relief and reflection improvement. The stress distribution of coal seam in large scale is not clear due to the influence of diamond bead slit parameters and geological parameters, making it difficult to identify. In this paper, the finite element model with built-in Coulomb friction contact surface is used to simulate the stress distribution in coal with different angles, seam length, working face length, seam friction coefficient and different in-situ stress difference. This investigation is conducted to examine the stress distribution of parallel working face, vertical coal seam, and advance working face. The simulation results show that the mechanism of stress transfer in large scale diamond beaded rope saw cutting coal seam is mainly due to the tangential slip of coal body on both sides of seam surface, forming concentrative zone and pressure relief zone with axial distribution, center symmetry and phase. The pressure relief range and maximum pressure relief range of all three direction present a âsingle peakâ distribution with the change of angel α between slit and maximum in-situ stress, i.e. when α = 45°, both of them are maximum. The slit length mainly affects the stress distribution in the advancing direction of the working face, and the length of working face mainly affects the stress distribution in the direction of parallel working face and vertical coal seam, both of which are positively correlated with the pressure relief range and the maximum pressure relief amplitude. The friction coefficient of seam surface and the difference of in-situ stress affect the relative dislocation of coal body on both sides of seam surface, and they inhibit and promote the pressure relief range and the maximum pressure relief amplitude respectively, and are greatly affected by α . The simulation results above suggest that it is reasonable to select fracture and geological parameters in practical engineering.