Rock armour

[nichodees]

I need a detail for rock armouring for river bank stabilisation - notionally using 1.5-2ton flat faced boulders. Max. bank height is about 1.5-2m.

Do I need to backfill the rock armour with a particular grade of stone to avoid washout?

Any help appreciated (or ideally a nice dwg I can pass on to the contaractor...)

Cheers
Kyle

 

[bridgebuster]

I don't know if this will answer the question, but it's a link to various manuals by the Army Corps of Engineers, scroll down to coastal engineering - there's a manual in five parts, and some others that sound as if they might be of use.

http://www.usace.army.mil/publications/eng-manuals/em.htm

Some years ago, when I was a resident engineer, we placed 1000's of tons of armor without backfill.

You might want to try calling CONTECH - earth stabilization unit,

http://www.contech-cpi.com,

they have a number of alternatives to armor stone that are cost-effective, and environmentally friendly. I don't work for them but I met with some of their reps yesterday to learn about their products. They said that armor has fallen out of favor with some regulatory agencies.

 

[cvg]

a granular filter layer or filter fabric is generally considered essential under a layer of riprap. However, the details need to be engineered such as thickness of layer or fabric type, gradation of the material, compaction, etc. You will need an engineer to prepare this detail for you. The USACE coastal engineering manual might help, however there may be other better sources of information than that. Ask your geotech for a recommendation.