The inclination of drill holes in blasting operations can have a significant effect on the fragmentation of the rock mass. The choice of hole inclination, whether vertical or inclined, can impact factors such as the size distribution of the blasted rock fragments, the efficiency of the blasting process, and the overall cost and safety of the operation.
Here are some key points to consider:
Vertical Drill Holes
Vertical drill holes are commonly used in blasting operations.
- They are drilled straight down into the rock, perpendicular to the surface, therefore support high accuracy unlike inclined holes
- Vertical holes can provide good control over the direction of the blast and are often used when precision is required.
- The blast energy is concentrated in a relatively small area, which can result in a more efficient breakage of the rock.
- Vertical holes can create a deeper blast pattern, which may be suitable for certain applications, such as bench blasting in open-pit mines.
Inclined Drill Holes
- Inclined drill holes are drilled at an angle to the vertical (See attached image)
- The angle can vary depending on the specific goals of the blasting operation.
- Inclined holes can help to distribute the explosive energy over a larger area of the rock mass and increase fragmentation volume.
- This can lead to a broader and more even fragmentation pattern.
- The use of inclined holes can reduce the need for secondary breakage, as the rock may break into smaller fragments more easily due to the spreading of the blast energy.
- Inclined holes are often used in controlled blasting techniques, such as pre-splitting, where a narrow, controlled fracture is created before the main blast.
In general, the choice between vertical and inclined drill holes should consider factors such as the rock type, the intended fragment size distribution, the geometry of the blasting area, and safety concerns. Inclined holes can be advantageous for creating a better muck pile profile in some cases, especially in open-pit mining where material needs to be efficiently loaded and hauled. Fragmentation is influenced by various other parameters, including the type and amount of explosives, the timing of the blast, the hole spacing and pattern, and the condition of the rock.
In summary, the choice between vertical and inclined drill holes in blasting operations depends on the desired fragmentation outcome and the specific requirements of the project.
Credits to Blessing Olamide Taiwo.
