Flyrock Prediction Calculator

Flyrock is one of the most serious hazards in any blasting operation. It refers to rock fragments thrown beyond the intended blast area by the force of an explosion. Even a single uncontrolled fragment can damage equipment, halt operations, or cause injury, which is why predicting and controlling flyrock is a core part of responsible blast design.

The distance flyrock travels depends on a combination of factors, including burden, stemming length, hole diameter, explosive charge mass, and the resulting scaled depth of burial. Fragment shape also plays a role, since flatter, more aerodynamic pieces experience less air drag and travel further than blockier ones.

A flyrock prediction calculator helps blasting engineers estimate the most likely maximum throw distance before a blast occurs. Working from your specific blast parameters provides a data-driven basis for setting exclusion zones and adjusting your design to keep fragments contained. This supports compliance with safety regulations and gives crews greater confidence that the blast area is clear.

Effective stemming controls explosive gas expansion to minimise flyrock risk. Both the Terrock and McKenzie models heavily prioritise this factor, identifying the stemming length and the scaled depth of burial as the primary drivers of rock-throw distance.

For more information on flyrock prediction, take a look at our case study on reducing flyrock by improving energy retention, as well as our guide to understanding and minimising the risks of flyrock in mine and quarry blasting.

If you are having problems controlling flyrock, noise, airblast, or overpressure, take a look at the Varistem stemming plugs or contact us.