Bearing Capacity
Bearing Capacity
(OP)
I am building a slab and I will be using 12"x12" piles. I need to know the required length (depth) of the piles but I do not have a bearing capacity. I was given a Geotech "report" that was performed years ago. It is really not a report as I was only provided with the Boring Logs.
I was wondering if there is any way to calculate the bearing capacity with only the boring logs. The boring logs have a SPT for the deeper soils. Please advise, I need an estimate on this so that I do not have to overlengthen the piles.
Thanks in advance.
I was wondering if there is any way to calculate the bearing capacity with only the boring logs. The boring logs have a SPT for the deeper soils. Please advise, I need an estimate on this so that I do not have to overlengthen the piles.
Thanks in advance.





RE: Bearing Capacity
A pile supported slab is not for the faint of heart! You need good geotechnical and structural direction. If you have no expertise in either, steer clear.
RE: Bearing Capacity
I would appreciate any other responses.
Thanks
RE: Bearing Capacity
RE: Bearing Capacity
without being to critical if you do not know what to do and have no one to guide you you need a proffessional to advise.
RE: Bearing Capacity
B+W Engineering and Design
Los Angeles Civil Engineer and Structural Engineer
http://bwengr.com | http://bwstructuralengineer.com | http://bwcivilengineer.com
RE: Bearing Capacity
I am not a geotech engineer by far, but have been involved in a few geotechnical recomendations in Florida. I would like to emphasize that if piles are needed? Typically when we performed soil borings, we already were given a loading criteria for our foundation footings and slabs. But first we took the worst case scenerio (boring log with the lowest blowcounts). Then we calculated a settlement (inches) for that particular loading. Very often we never needed to go with piles and the soil conditions were adequate for a conventional spread footing layout and rarely needed piles. Just trying to think outside the box for you. First, see if you actually need piles.
RE: Bearing Capacity
brandonbw- The company that did the original testing and sampled the soils is no longer in business. That is one of the first things I tried and never could get a hold on anthing or anyone that could help me.
ironaddict- This is for a project with really thick layers of soft clay, there is no sand layer near (90') and therefore we are going with piles. This is very common for the area.
As I said before, this project will NOT be constructed without a geotechnical engineers professional assistance, I was just trying to get an estimate of the bearing capacity to see what length of piles to use and to start a construction budget. I have been researching and found that Meyerhoff proposed a correlation to determine bearing capacity depending on the N number from the SPT test. I do not know how accurate this is and dont seem to find much theory behind what he based himself.
RE: Bearing Capacity
the side shear is N-bar/50 (N-bar is the average N-value for the penetration into the bearing stratum). Units are TSF.
Use a safety factor of 3.
These Meyerhoff simplifications are not very precise, so you will really need a geotechnical engineer. You should get some ideas though.
f-d
¡papá gordo ain’t no madre flaca!
RE: Bearing Capacity