DL/T 5799-2019 in English

1. Standard positioning and scope of application

DL/T 5799-2019, as a mandatory standard for the power industry, systematically regulates the design and construction system of water-passing cofferdams for the first time. It is applicable to hydropower and water conservancy projects with a designed flow rate of 20-1000m³/s, especially for conditions where the flood and dry water level fluctuation is greater than 5m and the annual flow frequency exceeds 3 times.

2. Comparison of Technological Evolution

1. Three-level control of structural design

1. Weir head anti-scouring layer: concrete thickness ≥0.8m, set settlement joints (spacing 10-15m)
2. Slope transition layer: when single-width flow rate>40m³/(s·m), a filter cushion layer (thickness 0.5-1.5m) is required
3. Energy dissipation protection layer: when platform width ≥8m and flow rate>7m/s, use concrete flexible row

2. Innovative application of materials

• Cementitious gravel: cementitious material dosage 80-120kg/m³, 28-day strength ≥5MPa
• Bagged concrete: anti-impact flow velocity can reach 10m/s, thickness is calculated according to 0.1V² (V is flow velocity)

Typical engineering application case

A hydropower station adopts a pivot type cofferdam, through:

1. 1:4 slope optimization of the weir body
2. The elevation of the sill exceeds the downstream water level by 2.3m
3. Steel mesh gabion foot guard (single cage size 2×1×1m)

Successfully resisted the once in 50 years flood, saving 45 days of construction time compared to traditional solutions.