drilled pier installation with water at the bottom.
drilled pier installation with water at the bottom.
(OP)
So the county want a representative from the structural firm (me) and geotech at the site when they install these piers. The representative from the geotech. firm was there the whole day. I left after 4 pier installation. My question is, we specify to use (3)-#5 with ties at 48" o.c. We encountered some water in the hole so they decided to stick (3)-#5 without the ties so that you can lower the concrete pump hose all the way to the buttom so you can displace the water out. Is that common practice for residential construction? I was worried because how would we know that the rebars are lined up properly? The geotech guy told me it was ok. I didnt say anything because I felt that the geotech should be more in charge with the piers then I do. Comments?





RE: drilled pier installation with water at the bottom.
RE: drilled pier installation with water at the bottom.
http://www.krmconsultants.com
RE: drilled pier installation with water at the bottom.
RE: drilled pier installation with water at the bottom.
http://www.krmconsultants.com
RE: drilled pier installation with water at the bottom.
Dik
RE: drilled pier installation with water at the bottom.
COEngineer im not sure if such loading need the ties or not but i want to correct you that for what i beleive its not the goetech responsibility with regards the ties and rebars placements, your the structural representatives, it yours...hope that technically under such load your pile does not need ties and the rebars lined up properly.
[b]fratrowie[/]
RE: drilled pier installation with water at the bottom.
RE: drilled pier installation with water at the bottom.
RE: drilled pier installation with water at the bottom.
Most of the Pump Hoses I see are smooth, and the end piece does not have a connection. We have lowered the hose through a steel cage in 10" dia piers and withdrawn it during the tremie operation. Be that as it may, just put a rebar tie at the bottom of the vertical bars and maintain some control at the top. Longer piers may be more troublesome, requiring intermediate tie bars.
RE: drilled pier installation with water at the bottom.
RE: drilled pier installation with water at the bottom.
http://www.krmconsultants.com
RE: drilled pier installation with water at the bottom.
RE: drilled pier installation with water at the bottom.
groundwater, again ACI 336-3R in chapter 4 provide some criteria regarding to dewatering and seepage entering ratio and this should be reviewed by the geotech engineer
RE: drilled pier installation with water at the bottom.
RE: drilled pier installation with water at the bottom.
If the 3 bars were creating space issues, I would have gone to two bars with equivalent area, unless you needed this configuration for anything else such as lateral forces. My guess is the uplift forces provided by the geotech dictated the amount of steel.
As far as who is responsible, it is both of you. It is likely the geotech guy was a technician (especially if he was there all day), and to his knowledge, this installation method has worked fine. Are you sure that he knows what all the issues could be? It was your design. You should be making sure it is being followed. That is why you were asked to be there.
RE: drilled pier installation with water at the bottom.
I want to concentrate on the size of the pier.
In expansive soils, the majority of the pier will, sooner or later, be in tension. The issue of minimum dead load and surface area which will be 'grabbed' by the expansive soils in the upper 1/3 to 1/2 of the length is every bit as important as designing the pier to be in tension. In my experience, Larger pier diameters will experience significantly more uplift force. I keep to 10" (up to 35' long) or even 8" (up to 20') diameter piers for lightly loaded conditions.
My experience has been that smaller pier diameters in expansive clays always work better. The only cases of failure at the pier/stemwall connection, which I am aware of, have been after the piers have moved, moved a lot. I have kept the pier diameters as small as practical, for constructibility, and have experienced very little problems.