# Study on Stope Stability in Continuous Mining of Long-Dip, Thin Orebody by Room–Pillar Method

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## Abstract

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## 1. Introduction

## 2. The Particularity of Mining Long-Dip, Thin Orebody

## 3. Engineering Situation

## 4. Stope Mechanical Model of Room-and-Pillar Mining in Long-Dip, Thin Orebody

## 5. Numerical Simulation of Stope Stability of Continuous Mining in Long-Dip, Thin Orebody

#### 5.1. Justification of the Geomechanical Model

#### 5.2. Computational Scheme

#### 5.3. Analysis of Calculation Results

#### 5.3.1. Stress Analysis

#### 5.3.2. Displacement Analysis

#### 5.3.3. Plastic Zone Analysis

## 6. Proposals for Continuous Mining of Long-Dip, Thin Orebody by Room–Pillar Method

## 7. Conclusions

- (1)
- The Burgers model of rock mechanics is introduced into the mining of a long-inclined, thin orebody, the failure mechanism of the goaf roof of the long-inclined, thin orebody is studied, and the rheological mechanical model of the stope of the long-inclined, thin orebody is established, providing a theoretical foundation for the optimization of the stope design and stope support of this kind of orebody.
- (2)
- In the room–pillar mining of thin orebodies with a greater tendency to extend, the roof displacement of the stope is proportional to the mining depth, that is, the deeper the stope is buried, the larger the roof subsidence. For instance, the roof subsidence is only 2.99 mm, while the displacement of the roof increases to 26.2 mm after level 300 is mined. With the continuation of mining, the roof displacement of the upper stope that has been finished will not stop, but will continue to increase, with the increasing range becoming smaller and smaller.
- (3)
- When the same stope structural parameters are used to extract long-dip orebodies, as mining depth increases, the compressive stress on the pillars and roofs obviously increases. For example, the maximum principal stress increases from 15 MPa to 40.95 MPa, and the maximum tensile stress increases from 0.53 MPa to 1.449 MPa. As the stope continuously advances, the plastic zone scope becomes wider and wider. The failure mechanism of the rock mass also presents a variety of failure modes from single-compression shear failure to compression shear failure, tension shear failure, and so on. This shows that the stability of the stope tends to decline under the existing stope structural parameters.
- (4)
- For long-dip, thin orebodies mined with the room-and-pillar method similar to the Mengnuo Lead–Zinc Mine, although its mining conditions are different from those of pure deep mining, the influence of the continuous variation of mining depth on the stability of the stope should also be noticed. When mining the lower part of the orebody, the existing stope structural parameters should be adjusted appropriately, such as reducing the spacing of the room or pillar, increasing the size of the point pillars, and increasing the width of the room and bottom pillars and the continuous pillars, so as to ensure the long-term stability of the stope surrounding rock.

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## References

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**Figure 3.**Mechanical system of roof and pillar of long-inclined, thin orebody with room-and-pillar method.

Lithology | Density (g/cm^{3}) | Uniaxial Tensile Strength (MPa) | Elasticity Modulus (GPa) | Cohesion (MPa) | Friction Angle (°) | Poisson Ratio |
---|---|---|---|---|---|---|

Orebody | 4.15 | 1.2494 | 55.1 | 0.7036 | 33.93 | 0.319 |

Sandstone | 2.71 | 0.8922 | 18.4 | 0.6659 | 49.19 | 0.084 |

Lamellar limestone | 2.75 | 0.9801 | 21.1 | 0.5242 | 30.43 | 0.103 |

Crystalline limestone | 2.82 | 0.9314 | 67.5 | 0.5443 | 33.32 | 0.309 |

Phyllite | 2.64 | 0.5498 | 13.2 | 0.4448 | 32.05 | 0.300 |

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**MDPI and ACS Style**

Guo, Y.; Miao, Y.
Study on Stope Stability in Continuous Mining of Long-Dip, Thin Orebody by Room–Pillar Method. *Sustainability* **2022**, *14*, 9601.
https://doi.org/10.3390/su14159601

**AMA Style**

Guo Y, Miao Y.
Study on Stope Stability in Continuous Mining of Long-Dip, Thin Orebody by Room–Pillar Method. *Sustainability*. 2022; 14(15):9601.
https://doi.org/10.3390/su14159601

**Chicago/Turabian Style**

Guo, Yanhui, and Yichen Miao.
2022. "Study on Stope Stability in Continuous Mining of Long-Dip, Thin Orebody by Room–Pillar Method" *Sustainability* 14, no. 15: 9601.
https://doi.org/10.3390/su14159601