Numerical Analysis on the Influence of Joint Density on the Stability of Complex Jointed Roadway Surrounding Rock
Abstract
:1. Introduction
2. Summary of Engineering Background
3. Calibration and Construction of Parameters for the Complex Jointed Roadway Surrounding Rock Model
3.1. Calibration of Particle Micromechanical Parameters for the Surrounding Rock of the Roadway
3.2. Calibration of Micromechanical Parameters for Joint Surfaces
3.3. Construction of Complex Jointed Roadway Surrounding Rock Model
4. Analysis of the Influence of Joint Density on the Stability of Roadway Surrounding Rock
4.1. Analysis of Displacement Field Variation
- (1)
- With the location closer to the roadway sidewall, the impact of joint density on the deformation of the roadway surrounding rock becomes greater. The displacement values of the roadway roof, floor, and sidewalls are affected differently by joint density. From Figure 13c, it can be observed that as the joint density εf increases from 0 m/m−2 to 0.2 m/m−2, significant deformation first occurs in the sidewall of the roadway. The maximum displacement value of the right sidewall increases from 3 mm to 50 mm, an increase of 47 mm. From Figure 13b, it can be seen that when the joint density εf increases to 0.4 m/m−2, significant deformation subsequently occurs in the floor, with the maximum floor heave increasing to 46 mm. When the joint density εf increases to 1.0 m/m−2, the maximum displacements of the left and right sidewalls, roof, and floor reach 247 mm, 380 mm, 124 mm, and 234 mm, respectively. The convergence of the left and right sidewalls is 627 mm, and the convergence of the roof and floor is 358 mm. The analysis reveals the following reasons: as the roadway is excavated along the roof, both sidewalls and the floor consist of relatively weak coal layers, while the roof consists of mudstone and sandy mudstone. Therefore, the sidewalls and floor are the first to undergo significant deformation due to the influence of joint density, followed by the roof.
- (2)
- As the joint density increases, the main areas of deformation in the roadway surrounding rock extend from the shallow rock mass to the deep rock mass. Taking the deformation of the roadway sidewall as an example, from Figure 13c,d, it can be observed that when the joint density εf increases from 0 m/m−2 to 0.4 m/m−2, the main deformation of the right sidewall occurs at the 0–1.0 m range, while the main deformation of the left sidewall occurs at the 0–1.5 m range. When the joint density εf increases to 0.6 m/m−2, deformation of the surrounding rock starts at a distance of 2.0 m from the right sidewall, and the convergence of the right sidewall increases to 51 mm. When the joint density εf increases to 0.8 m/m−2, deformation of the surrounding rock begins at a distance of 2.0 m from the left sidewall, and the convergence increases to 31 mm. When the joint density εf increases to 1.0 m/m−2, the convergence of the surrounding rock from both sidewalls reaches 78 mm and 72 mm at a distance of 2.0 m from the sidewalls. It can be observed that the increase in joint density leads to a decrease in the overall bearing capacity of the roadway surrounding rock. Shallow rock mass deformation and damage are severe, and the load-bearing rock mass gradually transfers towards the surrounding rock.
4.2. Analysis of Stress Field Variation
- (1)
- During the process of stress redistribution in the roadway surrounding rock, the vertical stress of the roof and floor is released more significantly compared to the horizontal stress, while the horizontal stress of the sidewalls is released more significantly compared to the vertical stress. With the distance closer to the sidewall, the stress release ratio of the surrounding rock becomes greater. Taking the stress of the roof and floor surrounding rock as an example, when the distance from the sidewall is 1.0 m, the vertical stress release rate of the roof and floor are 92% and 98%, respectively, and the horizontal stress release rate are 42% and 46%; when the distance from the sidewall is 5.2 m, the vertical stress release rate of the roof and floor are 44% and 59%, respectively, and the horizontal stress release rate are −18% and −6%. It can be seen that with the increasing depth from the sidewall, the vertical stress of the roof remains in a release state, while the roof and floor show a zone of increased horizontal stress.
- (2)
- The horizontal stress of the roof and floor, as well as the vertical stress and horizontal stress of the sidewalls, gradually change from positive values to negative values, indicating a continuous zone of stress increase for the horizontal stress of the roof, the vertical stress of the sidewalls, and the horizontal stress of the sidewalls with increasing depth from the sidewall. When the distance from the sidewall is approximately 1.6 m, both sidewalls show a zone of increased vertical stress, with stress release ratios reaching −3.7% and −12.1%, respectively. When the distance from the sidewall is approximately 4 m, the surrounding rock shows a zone of increased horizontal stress, with the horizontal stress release rate of the sidewalls being −0.6% and −5.6%, respectively, and the horizontal stress release rate of the roof and floor being −13.6% and −5.5%, respectively.
4.3. Analysis of Force Chain Field Variation
4.4. Analysis of Energy Field Variation
5. Conclusions
- (1)
- As the distance from the sidewall decreases, the influence of joint density on the deformation of the surrounding rock mass increases. However, the displacement of the roadway roof, floor, and sidewalls is affected by joint density to varying degrees, mainly related to the rock’s lithology.
- (2)
- During the process of rock stress redistribution, the vertical stress of the roof and floor undergoes more significant release compared to the horizontal stress, while the horizontal stress of the sidewalls undergoes more significant release compared to the vertical stress. The increase in joint density leads to an increasing rate of stress release in the surrounding rock, causing the load-bearing rock mass to transfer to deeper layers.
- (3)
- The presence of joints weakens the overall bearing capacity of the surrounding rock. With the increase in joint density, the distribution of force chain networks gradually transitions from dense to sparse, and the strong force chain networks decrease. As a result, the overall bearing capacity of the surrounding rock decreases, and the range of deformation and failure of the sidewalls increases.
- (4)
- As the joint density continuously increases, the values of maximum released kinetic energy and residual released kinetic energy become larger. Excavation disturbance leads to increasingly severe damage to the roadway surrounding rock. When the joint density reaches a certain value, the roadway surrounding rock maintains a high energy level in the kinetic energy stability zone, indicating extreme instability in the roadway and the presence of sustainable deformation.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
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Minimum Particle Radius Rmin/m | Maximum Particle Radius Rmin/m | Elastic Modulus Εc/GPa | Stiffness Ratio kn/ks | Particle Density ρ/kg·m−3 | Friction Coefficient μ |
---|---|---|---|---|---|
6.0 × 10−2 | 8.0 × 10−2 | 10 | 1.5 | 2700 | 0.7 |
Linear Parallel Bond Model Parameters | Elastic Modulus Εc/GPa | Stiffness Ratio kn/ks | Friction Coefficient μ | Tensile Strength σc/MPa | Cohesion c/MPa | Friction φ/° |
---|---|---|---|---|---|---|
Main roof sandy mudstone | 3.1 | 1.4 | 0.577 | 12.7 | 14.1 | 20 |
Immediate roof mudstone | 1.9 | 1.4 | 0.577 | 12.5 | 7.2 | 20 |
Coal–rock | 1.1 | 1.4 | 0.577 | 6.2 | 7.5 | 20 |
Floor sandy mudstone | 3.2 | 1.4 | 0.577 | 11.0 | 13.0 | 20 |
Smooth Joint Parameters | Normal Stiffness kn/GPa | Shear Stiffness ks/GPa | Friction Coefficient μ | Tensile Strength ten/MPa | Cohesion c/MPa | Friction Angle φ/° |
---|---|---|---|---|---|---|
Main roof sandy mudstone | 0.4 | 0.6 | 0.8 | 0 | 0 | 40 |
Immediate roof mudstone | 0.4 | 0.1 | 0.8 | 0 | 0 | 35 |
Coal–rock | 0.4 | 0.1 | 0.13 | 0 | 0 | 31 |
Floor sandy mudstone | 0.4 | 0.5 | 0.4 | 0 | 0 | 37 |
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Wang, W.; Wu, C.; Yang, Y.; Peng, X.; Jiang, L.; Huang, Y. Numerical Analysis on the Influence of Joint Density on the Stability of Complex Jointed Roadway Surrounding Rock. Sustainability 2023, 15, 13561. https://doi.org/10.3390/su151813561
Wang W, Wu C, Yang Y, Peng X, Jiang L, Huang Y. Numerical Analysis on the Influence of Joint Density on the Stability of Complex Jointed Roadway Surrounding Rock. Sustainability. 2023; 15(18):13561. https://doi.org/10.3390/su151813561
Chicago/Turabian StyleWang, Wenhai, Chaolei Wu, Yiming Yang, Xiaohan Peng, Lishuai Jiang, and Yifeng Huang. 2023. "Numerical Analysis on the Influence of Joint Density on the Stability of Complex Jointed Roadway Surrounding Rock" Sustainability 15, no. 18: 13561. https://doi.org/10.3390/su151813561