Underground construction

Pages:282-303
32. Underground construction
32.1. General provisions
32.1.1. Tunnelling operation should be carried on in accord-
ance with plans approved by the competent authority.
32.1.2. All occupied workplaces underground should be
inspected at least once in every shift.
32.1.3. Places occupied by solitary workers should be inspect-
ed at least twice in every shift.
32.1.4. At least once in every week, thorough inspections
should be made of all machinery, equipment, structures, supports,
roadways, means of egress, magazines, medical facilities, sani-
tation and working places.
32.1.5. All workers should be withdrawn from underground
workings if:
the ventilation fails; or
other imminent danger threatens.
32.1.6. Parts of underground workings found to be dangerous
should be fenced off.
32.1.7. A telephone system should be maintained from the
vicinity of the face of underground workings to the surface with
stations at intermediate workplaces.
32.1.8. In underground workings that are Wet, the workers
should be provided with waterproof clothing and boots.
32.1.9, In tunnels and other underground workings where
an explosive mixture of gas such as methane and air may form,
operations should be carried on in accordance with national
or other official regulations applying to gassy mines.
32.1.10. In these cases referred to in paragraph 32.1.9, in
particular:
(a) all electrical equipment and conductors should be flame-
proof or intrinsically safe;
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Underground construction
the current should be cut off from all electrical equipment
and conductors when the content of flammable gas in the
general body of the air exceeds safe limits;
no blasting should be done at any place where the content
of flammable gas in the atmosphere exceeds safe limits;
suitable gas detectors and gas alarms should be provided;
the atmosphere should be tested at suitable intervals in every
shift;
all workers should be withdrawn from the underground
workings when the content of flammable gas in the general
body of the air exceeds a percentage to be determined by the
competent authority; and
no worker should be allowed to carry matches or cigarette
lighters underground.
32.2. Shaft sinking
General provisions
32.2.1. Every shaft not sunk through solid rock should be
cased, lined or otherwise made safe.
32.2.2. Shuttering for masonry lining of shafts should only be
removed gradually as the masonry progresses.
32.2.3. As far as practicable, workers employed in sinking
shafts should be protected against falls of objects.
32.2.4. Workers employed on sinking shafts should be provided
with staging, scaffolds or cradles from which they can work safely.
32.2.5. Staging, scaffolds and cradles should, if necessary for
the maintenance of adequate ventilation in the shaft, be provided
with grids or other suitable devices.
32.2.6. As soon as practicable, the shaft top should be protect-
ed by adequate fencing, or guard-rails and toe-boards and gates.
32.2.7. When a shaft is being sunk through water-bearing
strata, adequate means of escape from the bottom should be
provided.
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