Estimate the head loss and required burial depth of an inverted siphon from pipe diameter, flow and terrain, for farmland water conservancy and water-supply crossings.
沿程损失按 λ = 0.025、内径 D = 1.0 m 计算，局部损失按进出口与弯头合计 Σζ = 1.5 计算；总水头损失再加 0.3 m 安全裕度即为倒虹吸最小埋深。
| Item | Formula / Note | Source / Standard |
|---|---|---|
| Head loss of an inverted siphon | Total loss = friction loss plus local losses at inlet, outlet and bends | GB 50288-2018, Standard for design of irrigation and drainage engineering |
| Friction loss | h_f = lambda · ( L / D ) · v^2 / ( 2g ) | Weisbach J. (1845), Lehrbuch der Ingenieur- und Maschinen-Mechanik |
| Local loss | h_j = zeta · v^2 / ( 2g ), where zeta is the local loss coefficient | Classical hydraulics; empirical values for inlet and outlet coefficients |
| Cover depth and velocity | Cover must satisfy anti-float, frost and load requirements; velocity should not be too low to avoid siltation | GB 50288-2018, Standard for design of irrigation and drainage engineering |
倒虹吸（水头损失）埋深。免费在线工具，纯前端处理，数据不上传，保护隐私安全。