Page 169 - Water Standards
P. 169

1) Reinforcement subsection: the ring direction reinforcement
                                of circular tunnels can be divided into roof arch, side arch
                                and bottom arch. For large diameter cross sections, further
                                subsections are needed, according to the process, trans⁃
                                portation and installation conditions. Ring direction rein⁃
                                forcement of the door⁃shaped tunnel can be divided into
                                the horizontal reinforcement in the roof arch, side wall
                                and bottom floor, together with the “L” reinforcement in
                                the side wall. The reinforcement in high side walls can be
                                divided into in line with the pouring height of each layer.
                                Axial reinforcement shall be divided according to the
                                length of the pouring section.
                             2) Reinforcement installation: all reinforcement bars shall be
                                in⁃situ installed. For roof arch or the side arch of circular
                                tunnels, the reinforcement should be installed after the
                                formwork is set up. For side walls in the door⁃shaped
                                tunnel and bottom arch in the circular tunnel, the rein⁃
                                forcement should be installed before the formwork is
                                set up.
                           6  Construction of formwork shall meet the following require⁃
                       ments:
                             1) Tunnel lining formwork, which can be ordinary formwork,
                                steel⁃formwork jack plane, sliding formwork and pulling
                                formwork, scraper formwork, shall be selected according
                                to the lining construction procedure, construction condi⁃
                                tions, design requirements, surrounding rock conditions
                                and section shape and size. For long tunnels with good sur⁃
                                rounding rock, a full⁃section steel⁃formwork jack plane
                                should be the best choice.
                             2) The formwork loads shall be added with the weight of the
                         1 6 2
   164   165   166   167   168   169   170   171   172   173   174