Initial weighting strength control of thick and hard roof based on pre-splitting blasting of whole roadway roof: numerical model and engineering verification
Thick and hard roof poses safety hazards to initial mining and caving of the working face due to its good integrity and large modulus. Taking the initial mining of No. 24110 working face in Nanyangpo mine as the background, this study proposes the “shallow-hole intensive blasting-deep-hole direction...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-09-01
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| Series: | Results in Engineering |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2590123025028579 |
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| Summary: | Thick and hard roof poses safety hazards to initial mining and caving of the working face due to its good integrity and large modulus. Taking the initial mining of No. 24110 working face in Nanyangpo mine as the background, this study proposes the “shallow-hole intensive blasting-deep-hole directional pressure relief” technology based on the roof pre-splitting of the whole roadway pressure relief concept: shallow-hole blasting creates weak surfaces in the shallow roof to ensure the lower layer breaks first and the main roof caves later during initial weighting; deep-hole blasting directionally weakens the main roof, realizing zonal caving of the roof and “dividing the whole into parts” for energy release. Numerical simulations show that with roof pre-splitting of the whole roadway, the working face advance distance for the first roof caving is 20 m earlier than that without pre-splitting. Initial weighting occurs at 60 m advance, with the main roof completely caving. The peak stress concentration of the stope coal wall and roof is significantly reduced. The roof caving morphology changes from the “O-X” type without pre-splitting to a fracture with a “W” shape at its center, avoiding strong mining pressure caused by overall caving of thick and hard roof and reducing accidents like support crushing and coal wall spalling. Field measurements of No. 24110 working face show initial weighting occurs when the head advances 54.7 m and the tail 82.7 m, with a calculated initial weighting step distance of 68.7 m, showing good agreement and being close to the simulation results. Weighting features low intensity and short duration, with no obvious spalling in roadways and no large deformation of surrounding rocks, ensuring safe and efficient passage through the initial caving stage. This study provides a new pressure relief method for initial mining under similar conditions, offering reference for reducing weighting intensity and optimizing initial weighting step distance in mining engineering. |
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| ISSN: | 2590-1230 |