Spacing

What is this formula?

Spacing is the distance between adjacent blast holes in the same row. Together with burden, it defines the drilling pattern and strongly influences fragmentation, muck pile shape, vibration levels, and explosive energy distribution.

A common preliminary design approach estimates spacing as a multiple of the burden.

When to use it

Use this formula when:

- Designing drilling patterns.

- Planning bench blasting operations.

- Estimating blasted rock volume.

- Optimizing fragmentation.

- Adjusting explosive energy distribution.

Example

A mine uses a burden of 5.0 m and a spacing-to-burden ratio of 1.3.

Data:

B = 5.0 m

r = 1.3

Formula:

S = r × B

Substitution:

S = 1.3 × 5.0

Result:

S = 6.5 m

The recommended spacing between adjacent holes is 6.5 meters.

Applications

- Surface mining

- Quarry blasting

- Bench blasting design

- Fragmentation control

- Blast optimization

- Production planning

Note

This formula is an empirical design guideline. Actual spacing depends on rock properties, burden, explosive type, hole diameter, initiation sequence, bench geometry, and desired fragmentation. Typical spacing-to-burden ratios often range from approximately 1.0 to 1.8, although site-specific optimization is usually required.