Steel Pile Friction
Steel Pile Friction
(OP)
I am designing a temporary retaining wall consisting of steel soldier piles and wood lagging. The wall will have to be removed, so I am planning to set the steel piles in drilled holes about 16 feet bgs and then backfill the holes around the piles with class 2 base rock. To remove the piles, I want to use a large excavator and lift them out of the gravel filled holes. What do you think is a suitable friction force to use in order to calculate the required force that will be required of the excavator to lift the piles out of the holes?
These will be W12x50 piles, 22 feet long (16 feet bgs) set in 18-inch diameter holes. The excavator will be able to sit on relatively flat ground at a close distance to lift the piles out. With those parameters, the excavator can lift about 20k vertically.
These will be W12x50 piles, 22 feet long (16 feet bgs) set in 18-inch diameter holes. The excavator will be able to sit on relatively flat ground at a close distance to lift the piles out. With those parameters, the excavator can lift about 20k vertically.





RE: Steel Pile Friction
RE: Steel Pile Friction
RE: Steel Pile Friction
RE: Steel Pile Friction
Usually, the soldier beams are cut off about 3 or 4 feet below finished grade with the rest of the system being abandoned in place. Full removal can sometimes cause voids and settlement problems.
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RE: Steel Pile Friction
Again, the only question I have is how much friction to use in my calculations to pull the piles out of the ground. I don't care if the wall deflects an inch or two. When we build the big wall below the temporary wall, all of the soil will end up getting reworked and compacted. The only thing that will remain are the holes filled with base rock.
RE: Steel Pile Friction
Just a thought looking at the ease of removal of piles first. I presume that in reoving the piles you would first remove the backfill against the wall, then the lagging. Could you use a hydovac truck to remove the stone fill from the pile holes. At least some can be removed by this process and allow you to use less force in removing the H-piles.
Alternatively the brute force approach would require you to calculate the frictional resistance afforded by the gravel on the pile. Friction values of stone against steel are available in the literature or some close assumption can be used, and as well one needs to add the weight of the pile and stone, and some frictional resistance of the stone against the excavated pile hole. Pouring some water down the pile holes can possibly assist in friction reduction.
Nice problem to play around with numbers and concepts
RE: Steel Pile Friction
Another way to look at it is from a pile driving standpoint. If it takes a 5000lb hammer dropping 8ft to drive a pile that last 2", how much do you think it will take to get pull it out? The trick is getting the pile to start pulling out.
Brad
RE: Steel Pile Friction
RE: Steel Pile Friction
RE: Steel Pile Friction
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RE: Steel Pile Friction
RE: Steel Pile Friction
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