Page 172 - Water Standards
P. 172

component shall be decided based on comprehensive analysis of the
                       surrounding rock stability, the stress of the component, and the pre⁃
                       fabrication, transportation and installation of the precast component,
                       as well as backfilling.
                           2    The installation of concrete precast components shall be
                       carried out by an installation jack plane. During transportation, the
                       components are folded and located at the lower part of the jack plane,
                       and unfolded and installed at the installation place.
                           3  The connector of the precast components shall be constructed
                       according to the design requirement. In rigid connectors, a step⁃gap
                       shall be left for the connecting with reinforcement bar extending out
                       and weld centre⁃to⁃centre when the component is in position, and
                       then being poured the second stage concrete at the connector. Flexible
                       connectors should be used if little compression deformation or
                       rotational deformation is allowed at the location of the connector.
                           4  Watertight seal construction shall meet design requirements,
                       and the regulations in Article 2   7   25 of this specification shall be re⁃
                       fered to.
                           5  The contact surface of the joint shall be roughened, cleaned
                       and filled up with mortar that has the same strength grade as the con⁃
                       crete, and pointing on the surface of the circular seam shall be
                       carried out.
                       3   5   6  Tunnel grouting shall be carried out according to the regula⁃
                       tions in SL 62  
                       3   5   7  The operational security of tunnel construction shall meet the
                       following requirements:
                           1  The transportation, storage, processing, in⁃situ charging of
                       the blasting material, as well as the treatment of misfire, shall all be
                       carried out according to relevant safety operation specifications. The
                       selected blasting material shall be in accordance with relevant national
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