A revet mattress is chosen by the speed of the water it must hold, the bank soil and slope, and the stone you can get. IRC:SP:116-2018 gives indicative tables for all three — here they are, with a selector.
Critical velocity = no movement of the fill. Check the chosen thickness against tractive shear (IRC:SP:116 cl 7.3) and keep the mattress at least twice the median stone size.
| Type | Thickness (m) | Stone size (m) | d50 (m) | Critical velocity (m/s) | Limiting velocity (m/s) |
|---|---|---|---|---|---|
| Revet mattress | 0.15–0.17 | 0.07–0.10 | 0.085 | 3.5 | 4.2 |
| Revet mattress | 0.15–0.17 | 0.07–0.15 | 0.11 | 4.2 | 4.5 |
| Revet mattress | 0.23–0.25 | 0.07–0.10 | 0.085 | 3.6 | 5.5 |
| Revet mattress | 0.23–0.25 | 0.07–0.15 | 0.12 | 4.5 | 6.1 |
| Revet mattress | 0.30 | 0.07–0.12 | 0.1 | 4.2 | 5.5 |
| Revet mattress | 0.30 | 0.10–0.15 | 0.125 | 5 | 6.4 |
| Gabion | 0.50 | 0.10–0.20 | 0.15 | 5.8 | 7.6 |
| Gabion | 0.50 | 0.12–0.25 | 0.19 | 6.4 | 8 |
Critical velocity: the fill does not move. Limiting velocity: modest deformation, without materially affecting the channel. The figures come from full-scale tests at Colorado State University.
| Bank soil | Max velocity (m/s) | Bank slope | Minimum thickness (m) |
|---|---|---|---|
| Clay, heavy cohesive soil | 3.05 | flatter than 1:3 | 0.23 |
| Clay, heavy cohesive soil | 3.96–4.88 | flatter than 1:2 | 0.30 |
| Clay, heavy cohesive soil | any | steeper than 1:2 | 0.45 or more |
| Silts, fine sand | 3.05 | flatter than 1:2 | 0.30 |
| Shingle with gravel | 4.88 | flatter than 1:3 | 0.23 |
| Shingle with gravel | 6.01 | flatter than 1:2 | 0.30 |
| Shingle with gravel | any | steeper than 1:2 | 0.45 or more |
Use this table for a preliminary thickness when there is no detailed soil investigation.
Revet mattresses to IS 16014:2024 in 6×8 mesh, 0.17, 0.23 or 0.30 m thick, galvanized or PVC coated, and 0.5 m gabion boxes where the velocity needs them.
Usually 0.17, 0.23 or 0.30 m, chosen from the flow velocity, bank soil and slope. IRC:SP:116 Table II-1 gives 0.23–0.25 m with 70–150 mm stone holding 4.5 m/s, and 0.30 m with 100–150 mm stone holding 5.0 m/s without the stone moving.
The velocity at which the stone fill starts to move: 3.5–5.0 m/s for 0.15–0.30 m mattresses and 5.8–6.4 m/s for 0.5 m gabions, depending on stone size (IRC:SP:116 Table II-1).
Stone of 70–150 mm for most mattresses, with the mattress at least twice the median stone size.
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