Highly improved drilling machines and mucking machines have been used for the tunnel
construction in Japan. To have rapid construction, the roles of blasting operation have been
growing more important. At the most tunneling of present, packaged explosives have been used
for a blasting in Japan. Under this circumstance, a blasting system of ANFO explosive using a
loader has been used recently for a tunnel blasting. However, this system has some problems,
such as a useless explosive in wet boreholes, bad after fumes and the ammonia gas due to the
decomposition of ammonium nitrate in contact with the sprayed concrete in tunnel.
A blasting system using bulk emulsion explosives with loading machine is used practically in
overseas. However, it is difficult to introduce this system to Japanese tunneling because of the
Japanese Explosives Control Law. The mechanical loading of emulsion explosive is required the
development of an emulsion explosive composition and blasting system suitable for tunneling
in Japan. Authors have developed a bulk emulsion explosive composition and blasting system to
comply with the regulations, and the field blasting tests were carried out to confirm actual
operations and blasting effects in three tunnels.
"Emulsion unit" used for explosive loading mainly consists of emulsion tank, pump and hose.
We have two units. One is "one - hose type" and the other is "two - hose type". An emulsion pump
is a mono progressive cavity pump, which it is called a mono - pump, and the emulsion delivery
rate is 25 kilograms per minute.
As a result of the field tests, safety is improved at the face, because the loading time can be
reduced. And the cycle time is less than that of packaged products.