Page 178 - Water Standards
P. 178
3 7 7 Steel bar installation shall meet the following requirements:
1 For construction by ordinary forms, the vertical steel bars
shall be installed in advance of the formwork erection, and the cir⁃
cumferential steel bars shall be installed after erection.
2 For construction by sliding formwork, vertical steel bars shall
be installed by subsection, and the circumferential steel bars shall be
installed as concrete being poured.
3 7 8 Concrete lining shall meet the following requirements:
1 The subsection elevation for shaft concrete lining shall be de⁃
cided according to the surrounding rock stability condition, lining
structure type and pouring method.
1) If the surrounding rock stability is poor, the shafts should
be excavated by subsection, and lined by subsection.
2) When the lining structure type is changed, the changing
point should be poured by subsection.
3) When the ordinary form is used in the pouring of large sec⁃
tion shafts, it can be divided into an even number of
blocks for pouring, according to form structure, mixing
and transportation capacity.
2 The concrete placement method shall be decided according to
the construction condition. When the shaft depth is within 15m, a de⁃
scent control tube can be directly used to convey the concrete mixing
into position. If the shaft depth is between 15 - 100m, the concrete
should be transported via a vibrating chute to the pouring platform at
the bottom, and then put in place by a descent control tube. If the
shaft depth is too deep, or the batching plant is located at the shaft
bottom, concrete mixing should by hoisted to the position with a
bucket.
3 Sliding form should be used for shaft concrete lining. The
form can be made into a whole structure or assembled structures ac⁃
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