Study on Overlying Strata Movement and Surface Subsidence of Coal Workfaces with Karst Aquifer Water
Abstract
:1. Introduction
2. Numerical Simulation
2.1. Engineering Background
2.2. Model Establishment and Parameters Selection
2.3. Overlying Strata Movement under the Condition of Karst Aquifer without Water
2.4. Overlying Strata Movement under the Condition of Karst Aquifer with Water
3. Theory Model of Surface Subsidence under the Condition of Karst Aquifer with Water
3.1. Calculation Model of Surface Subsidence Caused by Aquifer Drainage
3.2. Theoretical Calculation
4. Engineering Measurement and Analysis
4.1. Observation Scheme
4.2. Results and Analysis
5. Discussion
6. Conclusions
- (1)
- Compared with the karst aquifers without water, the movement and deformation characteristics of overburden for the karst aquifers with water drainage were quite different, while the collapse angle of overburden was roughly the same.
- (2)
- With the advance of the workface, the fracture caused by mining activities can penetrate to a karst aquifer and the water in the aquifer can flow to the workface along the fracture. The water drainage can decrease the osmotic pressure of aquifer, increase the effective stress of fractured limestone and the compression of aquifer, which can intensify the surface subsidence.
- (3)
- The maximum surface subsidence of mining area for the karst aquifer without water drainage was about 0.6 m, and the maximum surface subsidence of the mining area when considering water drainage was about 0.73 m. Therefore, the surface subsidence caused by drainage of multi-aquifer accounted for 17.8% of the total surface subsidence.
- (4)
- Based on the effective stress principle modified by the Biot coefficient αb, the axial deformation of aquifer with considering water drainage can be obtained, and the field-monitoring results of surface subsidence can also verify the accuracy of the theory-model results.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
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Rock Type | Thickness (m) | Density (kg/m3) | Bulk /(GPa) | Shear /(GPa) | Internal Friction Angle /(°) | Cohesion /(MPa) | Tensile Strength /(MPa) | Permeability Coefficient /(pa−1s−1) | Initial Gap Width /(mm) | Residual Gap Width /(mm) |
---|---|---|---|---|---|---|---|---|---|---|
Limestone | 110 m | 2800 | 5.57 | 4.53 | 38 | 11.4 | 6.7 | 110 | 0.2 | 0.05 |
Mudstone | 10 m | 2700 | 2.86 | 1.4 | 39 | 2.8 | 2.48 | 83 | 0.01 | 0.005 |
Changxing Limestone | 50 m | 2430 | 11.1 | 8.3 | 35 | 2.4 | 4.4 | 110 | 0.2 | 0.05 |
Sandy mudstone | 24 m | 2250 | 10.2 | 6.1 | 30 | 1.8 | 3.2 | 83 | 0.01 | 0.005 |
Mudstone | 4 m | 2550 | 5.8 | 3.2 | 30 | 1.2 | 3.25 | 83 | 0.01 | 0.005 |
Sandy mudstone | 4.5 m | 2250 | 10.2 | 6.1 | 30 | 1.8 | 3.2 | 83 | 0.01 | 0.005 |
Carbon mudstone | 1.5 m | 2450 | 3.2 | 2.8 | 30 | 0.7 | 1.8 | 83 | 0.01 | 0.005 |
C3 Coal | 2 m | 1470 | 1.19 | 0.82 | 25 | 1.3 | 1.79 | 83 | 0.01 | 0.005 |
Tonstein | 10 m | 2250 | 3.29 | 2.27 | 27 | 4.9 | 3.8 | 83 | 0.01 | 0.005 |
C1 Coal | 1 m | 1470 | 1.19 | 0.82 | 25 | 1.3 | 1.79 | 83 | 0.01 | 0.005 |
Mudstone | 13 m | 2550 | 5.8 | 3.2 | 30 | 1.2 | 3.25 | 83 | 0.01 | 0.005 |
Water | - | 1000 | - | - | - | - | - | - | - | - |
Advancing Distance of Working Face/m | Front Collapse Angle/° | Rear Collapse Angle/° |
---|---|---|
100 | 58 | 63 |
150 | 61 | 63 |
200 | 63 | 63 |
250 | 64 | 63 |
300 | 65 | 63 |
350 | 65 | 63 |
400 | 65 | 63 |
Advancing Distance of Working Face/m | Front Collapse Angle/° | Rear Collapse Angle/° |
---|---|---|
100 | 59 | 63 |
150 | 61 | 63 |
200 | 62 | 63 |
250 | 63 | 63 |
300 | 63 | 63 |
350 | 63 | 63 |
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Wang, Y.; Wu, G.; Liu, Y.; Cheng, Z. Study on Overlying Strata Movement and Surface Subsidence of Coal Workfaces with Karst Aquifer Water. Mathematics 2022, 10, 169. https://doi.org/10.3390/math10020169
Wang Y, Wu G, Liu Y, Cheng Z. Study on Overlying Strata Movement and Surface Subsidence of Coal Workfaces with Karst Aquifer Water. Mathematics. 2022; 10(2):169. https://doi.org/10.3390/math10020169
Chicago/Turabian StyleWang, Yuliang, Guiyi Wu, Yang Liu, and Zhanbo Cheng. 2022. "Study on Overlying Strata Movement and Surface Subsidence of Coal Workfaces with Karst Aquifer Water" Mathematics 10, no. 2: 169. https://doi.org/10.3390/math10020169
APA StyleWang, Y., Wu, G., Liu, Y., & Cheng, Z. (2022). Study on Overlying Strata Movement and Surface Subsidence of Coal Workfaces with Karst Aquifer Water. Mathematics, 10(2), 169. https://doi.org/10.3390/math10020169