Page 168 - Water Standards
P. 168

bottom arch: when the geological conditions are bad, and
                                digging is required at the same time as arching, pour the
                                roof arch (with joist) first and then pour the side walls
                                and bottom arch.
                           4  Joint treatment of the lining shall meet the following require⁃
                       ments:
                             1) Ring direction joint: for ring direction construction joints
                                of a free⁃flow tunnel without anti⁃seepage requirement, it
                                is allowed that the distributed reinforcement may not go
                                through the joint where no watertight materials shall be
                                filled and just the joint surface shall be roughened. For
                                ring direction construction joints of a free⁃flow tunnel with
                                anti⁃seepage requirement or pressure tunnel, surface
                                roughening treatment for the joint is required, and the dis⁃
                                tributed reinforcement shall go through the joint surface
                                and watertight sealing shall be filled. The ring direction ex⁃
                                pansion joints shall be treated according to design require⁃
                                ments.
                             2) Longitudinal joint: the bottom arch central angle of the lin⁃
                                ing block for circular tunnels shall be controlled to within
                                around 100°. The surface of longitudinal construction
                                joints, usually at places where the tensile stress and shear
                                stress are relatively low, shall be roughened. Key grooves
                                at the joint surfaces shall also be set up and watertight
                                sealing shall be installed in case of anti⁃seepage require⁃
                                ments. If bottom arch lining is carried out after side walls
                                and roof arch lining, the joint surface (surface of the in⁃
                                verse joint) shall be treated appropriately.
                           5  Reinforcement construction shall meet the following require⁃
                       ments:
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