Tieback Anchors at Water Table

[dcarr82775]

We have a project with some tieback anchors very close to water table (a little above and a little below) where they come through the wall. Obviously they then are anchored down in the soils below water table. We have done a couple of these and the contractor always cases the holes. On this project the contractor is adamant he doesn't need to case the holes and plans to 'open hole' the anchors.

This seem to me like it will not work. What are others experiences with this?

 

[GeoPaveTraffic]

Depends on the soils. If you are in sands, then an open hole will not work. If you are in clays, then an open hole may work depending on the clay strength and plasticity. If you have silt, anyones guess; but I wouldn't want to try an open hole.

Mike Lambert

 

[dcarr82775]

Sandy soils of course.

 

[GeoPaveTraffic]

I see no chance that the contract can keep an open hole in sands below groundwater.

Better watch/document to see how much material is being removed so you know how much compaction grouting or other remeadiation to plan for when the ground outside the wall starts to move.

Mike Lambert

 

[dcarr82775]

Thanks GPT. I know why he wants to try ($), but can't fathom why he thinks it will work. The drawings don't really allow it anyway, but I am sure he will have an argument that they really do.

 

[crcivil]

dcarr82775,

There is no way to know for sure if you can or can not work through open holes until the contractor gives it a try. Even if the drawings do not allow it, if he demonstrates in the field that it can be done, I don´t see why he should have any restriction for doing the job his own way, as long as the structural capacity and integrity of each anchor is succesfully tested.

Regards

 

[ACtrafficengr]

crcivil, will the anchors still pass the test after 10 years of exfiltration carrying the sand through the gap?

 

[crcivil]

I assume we're talking about temporary anchors ACtrafficengr. Regards.