Punctual destruction of masses and earthworks via explosives
Destruction of rocks for security purposes
In our work, we employ explosives in particular for the destruction of rocky masses of an unstable and threatening character, additionally or to support manual purging. In certain configurations, explosives can be preferred to other destructive techniques such as expanding cement, rockbreaking via pillows, boulders
This technique is of course shocking the first time. However, if perfect knowledge of the type of rocks (hardness, cracking, potental gaps, hetrogenous strata…) and of the correct mixture of different types of explosives available on the market, exactly the result and block size desired to be effected. It establishes a shot sequence which favours the ‘exit’ of the mass concerned before fragmentation where necessary. This also limits the spread of shockwaves too large for, for example, an urban area.
Using explosions has the advantage, beside the heavy administrative processes and constraints, to remove masses variable in size without impact, for example on a road located below. This is because it is perfectly feasible to transform a homogeneous and tough unstable mass into gravel, controlling the debris before it even reaches the ground.
It is also perfectly possibly to carry out a shot sequence that is highly controlled in terms of limited seismic wave thresholds and manage risks to work structures located in the direct vicinity.
Earthworks and explosives
Explosives can also be used according to the traditional blasting methods such as bank blasting in pits or in the context of altering roads to expand roadways.
This is done by advanced boreholes on the basis of an established shot sequence. A network of holes for mines (allowing for explosive charges to be introduced) which once charged and equipped with detonators, allow a shot sequence chosen to limit the unit load.
In effect, it would be possible to simultaneously blow up, via this same method, for example:
- 20 charges of 10 kilogram explosives, each of which posses the sole unitary charge at detonation of 200 kg of explosives, which create a seismic shock-wave
- It is possible to carry out the same shot sequence in a way which is 20 x less aggressive, using short intervals (generally 25 milliseconds, or otherwise according to need). This follows a staggered shot sequence which explodes the charges every 25 milliseconds. In this case the sole unitary charge remains a 10kg or 20 x less than the previous than the previous shot sequence. It is easy to grasp then that for the same shot, using the same supports and the same quantities of explosives, ncidence of seismic waves produced can be made to vary by 20 times more or less.
In this area, experience is king. No science offers absolute certainty about the results of a given shot sequence. It’s important then for clients, faced by these thorny subjects, to be able to completely rely on their company’s expertise.