Page 148 - Water Standards
P. 148

δ = pouring layer thickness;
                                       t = allowable interval time between pouring con⁃
                                       1
                                          crete;
                                       t = transportation time required for the concrete
                                       2
                                          mixing from the batching plant to the farthest
                                          pouring area.
                                                                            3
                           2    For hourly production capacity larger than 50m , an
                       automatic mixing plant should be employed; and for that less than
                          3
                       50m , a simple mixing station should be available.
                           3  The layout of the concrete system shall obey the following
                       principles:
                             1) The mixing plant ( station) shall be set up as near the
                                pouring site as possible, and shall meet the safe distance
                                requirements of blasting.
                             2) The topography shall be utilized properly to reduce the
                                quantity of work, and the mixing station shall be set up on
                                a stable and solid foundation.
                             3) Overall consideration shall be given to construction re⁃
                                quirements for the initial and later periods. Midway reloca⁃
                                tion shall be avoided as far as possible, and disturbance to
                                permanent structures shall be avoided.
                           4  The concrete system should have a centralised layout as far as
                       possible; a dispersed layout may be considered under the following
                       conditions:
                             1) In case of hydraulic structures scattered over a wide area or
                                the great elevation differences or with over⁃intensive pou⁃
                                ring, a  centralised  layout  will  result  in  the  far
                                transportation distance and difficult supply.
                             2) Concrete transportation routes at both river banks cannot
                                be connected.
                                                                            1 4 1
   143   144   145   146   147   148   149   150   151   152   153