Surface blasting - Blast design parameters
The controllable parameters of blasting are divided into three group s - (A) Blast design parameters (B) Physicochemical parameters of explosives (C) Initiation and delay timings (A) The basic blast design parameters are : H – Height of bench D – Blasthole diameter L – Drilled length of blasthole J – Sub drilling B – Burden S – Spacing I – Charge length T – Stemming length H – Height of the bench The vertical distance between the crest and toe of the bench is called the height of the bench. Figure 1 Opencast bench view D – Blasthole diameter The drill holes or the blasholes are drilled with the help of a drill machine. The blastholes are normally drilled in a circular shape. The diameter of the blasthole is the blashole diameter. Figure 2 Opencast bench view with blasthole showing the diameter of the hole. L – drilled length of blasthole The length of the drill hole from top to bottom is the drilled length of the blasthole or drill hole. Figure 3 Open...