Straight Shaft Drilled Piers
Straight Shaft Drilled Piers
(OP)
Hi,
When we are designing Straight shaft drilled piers especially for light light loaded structures, what parameters we need to consider other than skin friction and axial load? Is there any standard limit for minimum length of the drilled pier? Can some one clarify my doubt.
Thanks
When we are designing Straight shaft drilled piers especially for light light loaded structures, what parameters we need to consider other than skin friction and axial load? Is there any standard limit for minimum length of the drilled pier? Can some one clarify my doubt.
Thanks





RE: Straight Shaft Drilled Piers
** end-bearing if rock or till is close
** uplift loads - especially if in areas of frost heave and the depth of the drilled shaft is not much (may require sleeving through frost zone)
** some would argue that the depth to diameter must be greater than 5 or else it is a shallow foundation.
** "no support" if upper zone is peat or very soft clay
** support for equipment to install (drilling pad) if upper zone is peat, other paludal deposits or very soft clay.
** nature of the soils - in determining the "skin friction" or adhesion (see Tomlinson's alpha coefficient or Srinivasin/Focht's lamba coefficient).
** serviceability limit - i.e., amount of settlement or lateral deflection that is permitted by the structure without damage or loss of service
** probably others but some of our colleagues can add to the list.
RE: Straight Shaft Drilled Piers
RE: Straight Shaft Drilled Piers
Your design should be based on your boring logs-pen test data along with the reqt.s of what you will be supporting.
The last several years I have seen an asterisk and note on some Bridge layout/ shaft layout ..."Shafts shall penetrate a minimum of 2 diameters into hard blue shale" (or other matl.s as req'd) in other words no design is bullet proof if the folks on the ground are not well versed in what they are doing and paying attention to materials.
If your boring logs reflect a water table elev.- have it shown in the plans...this may change the methods by which the work will be accomplished.
RE: Straight Shaft Drilled Piers
Thanks
RE: Straight Shaft Drilled Piers
RE: Straight Shaft Drilled Piers
RE: Straight Shaft Drilled Piers
RE: Straight Shaft Drilled Piers
RE: Straight Shaft Drilled Piers
RE: Straight Shaft Drilled Piers
RE: Straight Shaft Drilled Piers
RE: Straight Shaft Drilled Piers
RE: Straight Shaft Drilled Piers
A frost wall is simply a wall that takes a continous wall footing below frost level, or in your case down to the N=20 soils.