Burden

What is this formula?

Burden is the shortest distance between a blast hole and the nearest free face. It is one of the most important design parameters in rock blasting because it controls the amount of rock broken by the explosive energy.

A common preliminary design method estimates burden as a multiple of blast hole diameter using an empirical burden ratio.

When to use it

Use this formula when:

- Designing production blasts.

- Establishing initial blast geometry.

- Estimating rock breakage volume.

- Optimizing fragmentation performance.

- Planning drilling patterns.

Example

A quarry uses a blast hole diameter of 165 mm and a burden ratio of 30.

Data:

D = 0.165 m

k = 30

Formula:

B = k × D

Substitution:

B = 30 × 0.165

Result:

B = 4.95 m

The recommended burden is approximately 4.95 meters.

Applications

- Surface mining

- Quarry blasting

- Bench blasting

- Blast pattern design

- Fragmentation optimization

- Explosive performance evaluation

Note

This formula represents a preliminary empirical design guideline. Actual burden values depend on rock strength, jointing, explosive type, hole inclination, bench height, initiation sequence, and desired fragmentation. Different mining operations may use burden ratios ranging from approximately 20 to 40 times the hole diameter depending on local conditions and design philosophy.