Guy Anchors / Passive Resistance in Uncontrolled Fill
Guy Anchors / Passive Resistance in Uncontrolled Fill
(OP)
Hey folks. Just like the title says:
I have a large site with a field of several feet of uncontrolled fill. You get a tree trunk here and there, occasional bricks/debris, large chunks of concrete, but mostly a fine SP.
My problem is there are a bunch of deadman guy anchors in that fill, and they've been there for at least 8 years, so I didn't get a great reaction when saying that it shouldn't be relied upon for foundation support.
Does anyone have any suggestions on shear strength parameters that can be used for analyzing lateral/passive resistance for guy anchors?
I included a photo from test pits. This is the best overall representation I could find.
I have a large site with a field of several feet of uncontrolled fill. You get a tree trunk here and there, occasional bricks/debris, large chunks of concrete, but mostly a fine SP.
My problem is there are a bunch of deadman guy anchors in that fill, and they've been there for at least 8 years, so I didn't get a great reaction when saying that it shouldn't be relied upon for foundation support.
Does anyone have any suggestions on shear strength parameters that can be used for analyzing lateral/passive resistance for guy anchors?
I included a photo from test pits. This is the best overall representation I could find.





RE: Guy Anchors / Passive Resistance in Uncontrolled Fill
Dave
Thaidavid
RE: Guy Anchors / Passive Resistance in Uncontrolled Fill
I'd probably treat it like a reasonably loose material, see if the numbers work with a conservative safety factor. If it doesn't, do a pull-test on the anchor. Most contractors who install guy anchors are setup to do a test like that for verification.
RE: Guy Anchors / Passive Resistance in Uncontrolled Fill
We had a pretty upset contractor when he was unable to install the helical anchors as designed due to unexpectedly high resistance.
Possible moral of the story is to agree with TLHS -- a pull test may be your best option.
RE: Guy Anchors / Passive Resistance in Uncontrolled Fill
I'm now looking at a different site now with a guyed tower (single tall mast and 3 anchors at 120 degrees radially), and there is about 20' of uncontrolled fill at the site and each of the anchors and the mast are shallow drilled shafts bearing within the fill. N-values within the fill range from 0 - 50bpf, mostly on the low side.
Intuitively the tower has been standing for years, and there's some phi and/or cohesion that is providing lateral-passive resistance for the drilled shaft guy anchors.
Undocumented/uncontrolled fill has become one of the most difficult issues I deal with at a multitude of sites.
RE: Guy Anchors / Passive Resistance in Uncontrolled Fill
I do a conservative approach to remove all the non engineered fill, then backfill with suitable material & compacted in maximum 200mm lift.