Tiebacks
Tiebacks
(OP)
We are designing a wall with sheetpiles and tiebacks (anchored at both ends to sheetpiles). Another feature that is added to the site will be a new concrete bleacher with the bottom of footings about 4 feet from the ground surface. The anchors in the original design are placed about 2 feet from the ground surface. My question is how can we protect the tiebacks from sagging? Loads from these concrete blocks above the tiebacks will add additional stresses. One option is to use rock anchors by installing the tiebacks without sheetpiles at the other end and grout them in rock or soil. The other option is to use a concrete conduit and run the tiebacks through them. The first option will be expensive, while the second one will be cheaper. Does anyone have expereince with such siituations? How to calculate the additional stresses in the tiebacks? Any practical problems from usning the concrete conduits?
Thanks
Thanks





RE: Tiebacks
Of course, all of this is dependent on the type of soil, magnitude of footing and loads, etc.
RE: Tiebacks
There are relatively few documented cases of tiebck failures. However, unintended bending of tie rods (in addition to tension) is one of the leading causes of tieback tendon failure. I would not install a footing on backfill, or in an embankment, over an unprotected tie rod. If you know that a tie rod will be bent, it should be designed for the combimed stresses of axial tension and bending. However, I would rather prevent the bending than design for it.
RE: Tiebacks
Have you considered using a back-to-back MSE structure to support the bleacher?
Jeff