SL253-2000 - Spillway Design Code

Author: None
Publisher:
Publish Date: 2000-12-01
Features: This specification retains the chapter structure of the original "Specification," which is divided into six chapters: General Provisions, Spillway Layout, Hydraulic Design, Building Structure Design, Foundation and Slope Treatment Design, and Safety Monitoring Design, along with five appendices. The main modifications to the original "Specification" are as follows:
(1) Clarifies the scope of this specification to include 1, 2, and 3-class riverbank spillways on rock foundations in medium and large-scale water conservancy and hydropower projects, and removes the content on "hydraulic design that considers spillway overflow over the factory roof and the outlet of flood discharge tunnels" from the original "Specification."
(2) Enriches the content on side-channel spillways and adds provisions on the layout of surface flow and eddy flow energy dissipation.
(3) In hydraulic design, additional coefficient values are specified for calculations such as negative pressure on the crest of a practical weir, WES weir flow capacity, broad-crested weir flow capacity, transverse water surface differences in side channels, side wall pulsating pressure, velocity at the jump nose, contraction section of the spillway, bend sections, and energy dissipation pools, and several calculation formulas and charts are supplemented.
(4) In the "Building Structure Design" chapter, the strength indicators of concrete are changed to a strength grade system; the shear strength indicators for the concrete-rock contact surface and weak interlayers are rewritten according to GB50287-99 "Specification for Geological Survey of Water Conservancy and Hydropower Projects"; the shear (pure friction) calculation formula for spillway/weir foundations is removed; two conditions—completed and construction—are added to the load combination for control sections; a load combination table for the side walls after the gate is added; and calculation formulas for the stability against overturning and sliding of the side walls are added.
(5) In the "Foundation and Slope Treatment" chapter, it is added that when determining the foundation surface, it is not advisable to rely solely on excavation methods and should also consider measures to improve foundation conditions through reinforcement.
(6) The observation design is renamed "safety monitoring design," and site inspections are included in the monitoring content. Instrument monitoring is divided into mandatory and optional categories, and the original classification of general and specialized observations in the "Specification" is no longer used.