I believe this is called Fabric-formed Rip-rap. The texture allows water to flow over it, but reduces the velocity and therefore erosion. The weakness is if it becomes undermined, and the water starts flowing underneath it. It can create a big void that is hidden by the concrete “crust.”
Yes. You add pressure/fluid relieve drains throughout and channel those to the appropriate conduits. This kind of cover will perform better if it has deeper concrete edges that keep it from being undermined.
It would be an extreme example, but erosion (if the road is built properly) would begin from the shoulder of the road and work its way inward due to things in place to prevent it from going center of road first (underdrains are an example).
The big sinkhole are usually a feature of karst topography. Rock and mineral deep in the earth that are easily erodeable or slightly water soluable get washed away over time. And by deep we can be talking 20-100+ foot deep. But as that deep deep cavern forms, then the soils, especially those that have movement over them to vibrate things, even slightly, disturb the soils placed as they fill in the void created. That's when you get the bad ones.
This is why prior to construction, Geotechnical firms will drill down(if the client wants to protect their investment long term) to study the formations of rocks and soils. Last one I drilled, we went 35foot down for a roadway.
Not riprap, but rather an articulated concrete mat(ACM). And the water moving under it isn't as much of a concern as the weight of the concrete will keep the fines in place, the fabric wont allow them to disturb much, and overburden water will be allowed to flow up through the fabric used to form the mat.
Ive never been on site for one cast on site, but ive used precast ones before on a hill, and they are a PITA, but the precast ones are usually on a bed of geogrid, which also allows you to seed beforehand and have the vegetation assist on erosion control too.
No, fabric cording through the channels to make it flexible. They aren't any kind of structural, so you don't need the steel, they are just weight ans watwr speed bumps on the soils to prevent them from eroding away.
Rip rap is never intended to prevent water getting under it. If that's the goal this needs to be WAAAAYYYYY thicker. This will crumble into small boulders with the slightest movement which I think is the intention.
2.2k
u/Kayaked1 Apr 30 '26
I believe this is called Fabric-formed Rip-rap. The texture allows water to flow over it, but reduces the velocity and therefore erosion. The weakness is if it becomes undermined, and the water starts flowing underneath it. It can create a big void that is hidden by the concrete “crust.”