Volume-IF - JantERmantER

DCPL-K4A02
On completion, the work will be finally checked and approved by the
Engineer. In case where excavation in soil, soft and decomposed rock
and/or hard rock are involved, the soil or soft and decomposed rock layers,
shall be removed by turn and levels of the underlying rock surfaces observed
to enable measurements. Further work shall be resumed after getting
clearance from the Engineer.
3.6.3 Excavation in Hard Rock
3.6.4 Blasting
3.6.4.1 General
Overburden, if any, consisting of top soil, ordinary and hard soil, soft
and decomposed rock as per classification of soil, which do not require
blasting shall be completely stripped off and the levels of the hard rock
surface shall be taken to enable measurement. Further work in hard rock
shall be resumed after clearance from the Engineer.
Personnel deployed for rock excavations shall be protected from all
hazards such as loose rock/boulder rolling down and from general slips of
excavated surfaces. Where the excavated surface is such that it is not
stable against sliding, necessary supports, props, bracings or bulkheads
shall be provided and maintained during the period of construction. Where
danger exists of loose rock/boulder falling from the excavated surfaces
deeper than 2 metres, steel mesh anchored to the lower edge of
excavation and extending over and above the rock face, adequate to
retain the dislodged material shall be provided and maintained.
In case where blasting, though otherwise required, is prohibited for any
reasons, the excavation shall be carried out by chiselling, wedging or
any other approved method. All loose or loosened rock in the sides shall be
removed by barring, wedging, etc.
Excavation shall be continued in hard rock to such widths, lengths,
depths and profiles as are shown on the drawings or such other lines and
grades as may be specified by the Engineer. As far as possible all blasting
shall be completed prior to commencement of construction. At all stages of
excavation, precautions shall be taken to preserve the rock below and
beyond the lines for the excavation, in the soundest possible condition.
The quantity and strength of explosive used, shall be such as will neither
damage nor crack the rock outside the limits of excavation. All
precautions, as directed by Engineer, shall be taken during the blasting
operations and care shall be taken that no damage is caused to adjoining
buildings or structure as a result of blasting operations. In case of damage
to permanent or temporary structures, Contractor shall repair the same
to the satisfaction of Engineer. As excavation approaches its final lines and
levels, the depth of the charge holes and amount of explosives used shall be
progressively and suitably reduced.
Unless otherwise stated herein, I.S. Specification IS:4081 "Safety Code for
Blasting & Related Drilling Operation" shall be followed.
(PCA.774.S034sca) V.II-D2/S-I : 8