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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