Seepage & Uplift – Quick Check (Bligh / Lane)

Preliminary check of creep length and uplift under a horizontal floor with upstream and downstream cutoffs. Based on Bligh / Lane concepts with a simple linear uplift distribution along the seepage path. SI units: m, kN/m³.

⟵ Hydraulic Jump & Stilling Basin Tool Anti‑Scour / Scour Depth Tool Headworks Design Workflow

1 Calculations – Heads & Geometry

Geometry is idealised as a horizontal floor of length Lfloor between a single upstream and downstream cutoff (sheet pile / key), founded on an impervious stratum.
Vertical distance from impervious stratum to upstream water surface.
Tailwater level or average downstream water surface, measured from the same datum.
Distance between upstream and downstream cutoffs (measured along the floor).
Vertical depth of the upstream sheet pile / key below the floor.
Vertical depth of the downstream sheet pile / key below the floor.
Both are reported; this selection decides which is used for the “OK / not OK” creep check.

2 Material & Safety Inputs

Uplift is checked against the self‑weight of the concrete floor only (no overburden). Use unit weights in kN/m³ and thickness in m.
Typical reinforced concrete ≈ 23–24 kN/m³.
Bligh recommended C ≈ 18 for fine sand, ≈ 15 for coarse sand; adjust per local code.
Often ≥ 1.2–1.5 for permanent structures; check local standards.