Purging unstable rocky areas
First of all, we are discussing manual purges, the eradication by elective break and the rock hazard concerned. Purging instabilities is a preliminary stage of all work on cliffs. In certain cases of urgent risk it can be the only work to carry out.
Security measures need to be undertaken beforehand via working ropes for the access. In addition purging pincers, known as ‘purging canes’ in industry jargon, are to be used.
However, said tool only adds a limited amount to human force. For larger faces, it is sometimes necessary to employ machine tools. This entails mechanized machine purges, using air bags, hydraulic cylinder spacers, ‘Boulders’ spacers, and other non-explosive ‘backfiring’ procedures.
However, purges often create a risk to infrastructure, personal assets, persons and commuters below as they are exposed to masses of varying size and character during their free-fall. This can have a destructive impact on anything in its path.
Given this, the level of protection to be placed below is directly linked to the character and size of the instabilities to remove. These initial contexts and constraints need to be carefully studied in order to establish in full the requisite technical solution. This will break the rocks as desired without creating too high a level of risk and damage to those below. For this reason explosives are employed in certain cases. This allows the desired block character to be attained through the drop height and constraints on material spreading.