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Excavator creates supporting wall with boulders.
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Previously:
Dry stone wall building technique - GIF
Massive wall installation - GIF
Moving a one-million-pound wall - GIF
I've built a bunch of walls and this looks quite problematic to me.
This is a gravity wall, the resistance to tipping is solely the gravitational force of one block on top of another.
There is fabric behind the blocks, but it looks like the backfill is on top of the fabric and is the soil the second excavator brings in. It might be sandy, but there isn't much topsoil on the slope and the soil being placed looks like iron clay.
Water flowing is the enemy of the project and the faster it flows, the more damage it can do. So, the object of these kinds of structures is to spread the flow out so it slows down. You don't want pooling as that creates pressure. We always backfilled with crushed rock - not river rock. We also put fabric to keep the soil from moving and to keep the soil in place.
For any erosion control walls, I ever had any dealings with constructing. I always specified adding dead men anchors if the wall was to exceed than twice its thickness in height
Yes, that is an important consideration. "Deadmen" increase the horizontal width of the wall which can dramatically decrease the tipping the wall might experience. However, hydraulic pressure is a force that must be considered and if the force is at the top of the wall, that force can still cause a wall to tip - hence the need for leaky backfill that does not pool the water but rather lets it flow slowly and broadly to the base where it's force has less effect on tipping.Quote:
Originally Posted by Frank S
There was a wall I built that was about 14ft tall, had geo-textile material (think heavy thickness plastic webbing) extending 6ft minimum back from the face of the wall, and backfilled with compacted crushed rock (3/4 minus).
Seeing the huge hill behind this wall, it may last 40 years if all the perfect drainage and water flow engineering principles are used. BUT that huge hill will move, you just don't see it.
Water will make everything move over time, that big hill is the real thing to fix. Remove it totally and the problem goes away, and so does the natural beauty of the spot, with a very nice looking stone wall, that will get an aged patina.
But it will eventually be buried.