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Rip Rap Channel Design

Rip Rap Channel Design

Rip Rap Channel Design

(OP)
Can someone point me in the right direction to find the Army Corp of Engineer literature regarding the design of reip-rap channels?  I've done a web search and come up empty, and their website isn't all that helpful.

If there are other documents regarding this subject, I would love to hear about them as well.

Shane

RE: Rip Rap Channel Design

I WOULDNT RECOMMEND WEST CONSULTANTS - THEY BILLED MY CREDIT CARD A MONTH AGO AND I STILL HAVENT RECEIVED MY SOFTWARE

RE: Rip Rap Channel Design

Riprap channel design using Manning's equation is pretty straight forward:

n=d^(1/6) / [21.6 log(d/d50) + 14], where d = flow depth (NOT channel depth) in feet and d50 = average rock size, as follows:
NSA size    d50, ft
R1    0.0625
R2    0.125
R3    0.25
R4    0.5
R5    0.75
R6    1
R7    1.25
R8    1.5

You will have to run a few iterations to get n, but 0.07-0.10 are good starting points.

Size for velocity (under 10% long. slope, s) or shear (over 10%):
NSA size    v, fps    shear, lb/ft = Shear stress = d x s x density of liquid
R1        2.5      0.25
R2        4.5    0.5
R3        6.5    1
R4        9    2
R5        11.5    3
R6        13    4
R7        14.5    5
R8        14.5    8

It should be noted that R1 and R2 are generally not accepted in central PA, because they are not really available (small graded stone is usually classed by AASHTO or a DOT system).  Also, for all but the largest of projects, riprap is not actually graded, so spec on the high side (higher NSA #).  Finally, when costing out riprap versus synthetic liners, add a significant amount for machine placement, as the per ton or cf price is just what it will cost your client to have a big pile of rocks dumped in her driveway, not what is will cost labourers and machines working all week to place the stuff.  In reality, a reno mat is easier to place than R7 or R8.  After adding in the aesthetics of the final product (grass versus rocks), I usually go with a synthetic liner.

RE: Rip Rap Channel Design

A reference I have found very helpful is "River and Channel Revetments: A Design Manual",by Manuela Escarameia, published by Thomas Telford, London.

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