When it comes to rock excavating, blasting, ripping and breaking have been popular methods to excavate rock and has been a part of construction engineering for X number of years.
In any blasting situation, the geologic structure of the rock mass will be the most important consideration. Other considerations include the degree of scarring that would be acceptable since some areas can tolerate more blasting scars than others, cost, and safety. Remember that blasting cannot be performed in close proximity to populated areas.
To help you determine the most suited blasting procedure for you, here are a few procedures along with advantages and limitations.
Presplit blasting are blasted before production blasts. Procedure uses small diameter holes at close spacing and lightly loaded with distributed charges. A few prefer this method because it protects the final cut by producing a fracture plane along the final slope face that fracturesfrom production blasts cannot pass. Also, it can produce steeper cuts with less maintenance issues abd performs well in hard competent rock.
However, the small diameter borings limit the blasting depth to 15 m (50ft). Borehole traces are present for entire length of boring and it does not perform well in highly fractured, weak rock.
Next is smooth blasting where smooth blast holes are blasted after production blasts. The procedure uses small diameter holes at close spacing and lightly loaded with distributed charges. This produces a cosmetically appealing, stable perimeter. It can be done on slopes years after initial construction. In addition, drill hole traces are less apparent than presplitting and performs best in hard, competent rock.
But, similar to presplit blasting, there is a small boring diameter limits blasting depth to 15 m (50 ft). Borehole traces are present for much of the boring length. It does not protect the slope from damage caused by production blasting and also do not perform well in highly fractured, weak rock.