Question $1$: $,(50$ marks$)$

Design a $($from $1^{st}$ principles$)$ drilling, charging and timing round for a rectangular tunnel with the

following dimensions: Height $-3\mathrm{.}3$ m $,$ width $-3\mathrm{.}7$ m in a friable quartzite. Do not make use of a

computer model.

The proposed hole diameter is $48$ mm $.$ Final drill hole length is $3\mathrm{.}3$ m on a mechanised drill. Select:

an ANFO explosives type in your first proposed design and

bulk emulsion type explosives for the second design.

You may select your own initiation system $\frac{?}{s}$ for the $2$ different designs. Compare the drilling and

blasting cost per $m^3$ between the ANFO design and the bulk emulsion design.

Assume a drilling cost of R$44\mathrm{.}50$ per metre. ANFO $=>$ R$13\mathrm{.}00/$kg$,$ Emulsion $=>$ R$14\mathrm{.}75/$kg$,$ In$-$hole

detonator $=>$ R$42\mathrm{.}50/$unit and tamping cartridges $=>$ R $2\mathrm{.}30/$unit$.$

The average advance per blast is $3\mathrm{.}1$ m for the ANFO blast and $3\mathrm{.}2$ m for the emulsion blast.

Do you agree with the advances? Clearly show all the assumptions you are making.

Complete the table below and discuss the costs. $($Plan design is to the full drill depth and the actual is

to the full drill depth minus the socket remaining after the blast$)$

Costs per metre $=$ costs per metre advance $.$