Page 183 - Water Standards
P. 183

pipes according to the construction condition.
                             6) For the convenience of installation and overhaul, the
                                bottom clearance of the steel pipe shall be at least 60cm
                                higher than ground level.
                             7) To reduce errors caused by sunshine (temperature differ⁃
                                ence), measurements during construction should be carried
                                out at fixed times, or when the sunshine is not strong.
                             8) Other requirements shall meet the provisions in Article
                                4   1   17 of this specification.
                       3   8   5  The construction of reinforced concrete penstocks shall meet
                       the following requirements:
                           1  The construction of pipe bed and pipe supporter shall meet
                       the following requirements:
                             1) Pipe bedding excavation shall follow the requirements in
                                Section 2   3 of this specification.
                             2) The soil pipe bedding shall be compacted densely layer by
                                layer. Rigid pipe bedding cushions shall be laid on sound
                                rocks. Concrete or stone masonry shall be constructed fol⁃
                                lowing the requirements in Sections 2   7 and 2   8 of this
                                specification. The quality of soil filled on the top of em⁃
                                bedded pipes shall meet design requirements.
                             3) Asphalt painted on or asphalt felt laid between pipe body
                                and supporters shall meet the design requirements.
                           2  The construction of anchorage blocks shall meet the require⁃
                       ments in Article 3   8   4 of this specification.
                           3  Subsections and joints of pipes. The interval distance between
                       expansion joints of cast⁃in⁃place reinforced concrete should be 15 -
                       20m for soil foundations, and 10-15m for a rock base. There are two
                       types of pipeline joint, opening style and telescopic style, and
                       priority in selection shall be given to the latter. The width for the ex⁃
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