3.1 Drilling and blasting

•The face of the tunnel is made smooth with the help of hydraulic hammers.

•Holes of diameter 48mm to 51mm are drilled on the face of top heading or benching with the help of a machine called Boomer.

•The maximum length of the hole is kept 3m.

•The holes are filled with explosives and connected to a non electric detonator. The detonating mechanism is placed at least 500m distance from blast site.

•The detonator used for explosion is a non electric detonator and is commonly called as Shock Tube Initiator.

Boomer for hole drilling

Cortex tube for detonation purpose

Explosive