Long culvert on no slope
Long culvert on no slope
(OP)
Reviewing a design:
2 BOX culvert with a length of 120' on 0 slope (identical upstream & downstream elevation).
To reach the rock bedding, they've put the BOX 3' under the stream elevation (embeddding).
Is it me or this will affect:
1) Capacity of te culvert (I have to see the calculations yet)
2) Frequency of maintenance (sedimentation issue)
3) ...
2 BOX culvert with a length of 120' on 0 slope (identical upstream & downstream elevation).
To reach the rock bedding, they've put the BOX 3' under the stream elevation (embeddding).
Is it me or this will affect:
1) Capacity of te culvert (I have to see the calculations yet)
2) Frequency of maintenance (sedimentation issue)
3) ...





RE: Long culvert on no slope
RE: Long culvert on no slope
If 3-sided I would recommend cast in place footings and knee walls to keep the box at the higher elevation, unless it is designed for the loss of height. Also, the stream elevation may lower due to contraction scour which may help with this. On the other hand if scour becomes too large due to contraction and local abutment/pier scour, the rock will be exposed and an evaluation of whether the rock is erodible should be performed. In this case rock embedment of the footings may need to be considered.
If a 4-sided box just check to make sure the culvert was designed with the sedimenation issues in mind. You could also grade the channel to lower the elevation to the box bottom.
RE: Long culvert on no slope
RE: Long culvert on no slope
From my understanding, the 4-sided box isn't oversized and no analysis has been perform regarding scour/sedimentation issue.
Plus, from my own verifications, there's no rock 4' under the stream so...
RE: Long culvert on no slope
It's pretty hard to calculate a culvert with no slop (?!). You can do it but... you have to assume a minimum slope or a head differential from entrance to exit.
I'm trying to make my point about avoiding a 120' culvert on a flat slope. Option is to reprofilate the stream upstream (or downstream) to gain a little slope (say at least 0.1%).
RE: Long culvert on no slope