Calculating how deep to drive timber pilings (Gulf Coast Area)
Calculating how deep to drive timber pilings (Gulf Coast Area)
(OP)
I am an engineering intern assigned the task of creating a spreadsheet that calculates how deep to drive timber pilings for deep foundations and I was looking for some help on the best way to go about doing this. My goal is the spreadsheet spits out the depth after several variable inputs. The company is in the Galveston, TX area, and typically works with loose, medium dense, and dense silts and sands. We are a windstorm and structural engineering company, so these piling foundations must withstand hurriance and windstorm conditions typically found along the Gulf Coast region. I was working from the Meyerhof method for calculating piling depth using http://www.geotechnicalinfo.com/bearing_capacity_technical_guidance.html#deepfoundations
But I want to make sure I am headed in the right direction. This is my first post of course, and I hope that this is appropriate relative to the forum rules. Thanks in advance for your input.
But I want to make sure I am headed in the right direction. This is my first post of course, and I hope that this is appropriate relative to the forum rules. Thanks in advance for your input.





RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
How you put that in the program is interesting. I usually specify in the specs that when computed depth has been reached, you wait to see if what I say is true and use what ever method you have for evaluating the capacity then. It may take an hour or a day, depending.
Thus, does it make sense to neglect side friction for computation? Sounds weird.
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
Thank you for your response, and ideally I would like to use the skin friction variable in the calculation. So if you do have a method including Fs, then I am okay with it. Yes, that all makes sense, but remember this is usually all done in quartz dominated sand off the shores of Galveston. They compact the sand before they start driving piles, so its not like they are just driving into the soil as is. Point is, the only value I am concerned with, is how deep based soil type, piling diameter, and actually timber, concrete, or steel piling types. Is it possible to do this without taking into consideration the method for driving the piles?
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
Driving through a well compacted sand zone probably will call for assigning a higher friction there, but is your compacted zone encompassing the full pile depth? I doubt it.
My suggestion a this point is contact a well known coastal pile driving contractor and explain your situation. I find that most contractors are glad to pass on their experiences to an engineer, since many times contractors find they disagree with the engineer and this would be a breath of fresh air. I have found contractor contacts to be very valuable.
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
The following link might be useful in showing you various methods of computing piling capacity and the "accuracy" of such
http://www.fhwa.dot.gov/publications/research/infr... .
I might caution about something - that is preparing a "graph" of pile capacity vs depth. I have seen this done by others and you get this - now if I drive to 20 ft I have X tons. But at 21 ft I have X+Y tons - oops, at 22 ft, I have X-z tons - piles won't work that way.
Another source is Flaate and Olsen's papers on pile driving forumulas - with corrections and the use of Gates formula.
Just some additional thoughts.
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
Thank you for your response. When I come up with something on this I will post in here, and maybe you can take a quick glance at it. I'll take a look at your links.
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
Agree with oldestguy that the OP needs to get some advice from an old hand in piled foundations in the particular area. This is not a task for an intern without an appropriate mentor.
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
The old Timber Pile Manual from the 60s had most of its papers written by those from Louisiana - and they might be appropriate.
Some other references that the OP might be interested in:
http://www.fellenius.net/papers/204%20Tapered%20Pi...
http://www.raymondpile.com/images/Raymond%20Pile%2... (has one page giving an actual calculation)
http://www.pilelineonline.com/pdfs/IeC_GEO3%20tape...
http://krc.cbri.res.in/dspace/bitstream/123456789/...
Now we'll all be befuddled!
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
Your shaft resistance will be several times more than the tip resistance in soils such as you have described.
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
Link
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)
RE: Calculating how deep to drive timber pilings (Gulf Coast Area)