Gabion Slope Mattresses

[RAWeber]

Has anyone had much experience with slope mattresses? We are doing a scour remediation job for the State DOT and they love gabions and slope mattresses. They want stakes in the mattresses, but don't as of yet have any specification on them. Can anyone give me some good ideas as to how to space these things? We're using 4' long stakes in 6'x9'x12" matts.

Thanks,

Robert

 

[cvg]

I have used steel fence posts, driven through the gabion mattress at uniform spacing. The posts are driven flush, or till refusal, double wrapped with wire secure, and cut off flush with the top. Estimating the number of anchors required is more difficult and depends on soil conditions, water table, etc. Mostly, I want the anchors to prevent the gabions from lifting during high velocity flows, or to prevent them from sliding down the slope - either during construction or after. I recently used this technique on an emergency spillway which had high velocity flows. Construction problem occurred when the contractor had difficulty driving the fence posts the full 8' and hit a caliche layer (or rock cobbles). Most of the posts only were driven 4 - 6'. Spacing was 3' OC EW. This corresponds with the 3' nominal dimension of the gabion cells and diaphragms.

Chuck
cgopperton@stantec.com

http://www.stantec.com/

 

[ERWS]

Stakes are utilized only for construction of mattress on slopes steeper than 2:1 and typically are placed 6' on centers. Stakes should not be relyed on for shear resistance to Hydrolic flows. This should be a function of the weight per square foot of Gabions installed.
A #6 rebar 3-4' long and protruding 6" into basket would be enough to hold baskets.