Pile Foundation - Geotech Report Needed?
Pile Foundation - Geotech Report Needed?
(OP)
Hi All,
I have a general question and wanted someone else's thoughts. I have been tasked with engineering my first driven pile foundation for a 25' high Garage to hold a Vac Truck for sanitary sewer purposes. The garage is 40' x 40', with sub-par existing soils and a high water table. Seems like a pretty straight forward design, was planning to have 9 piles equally spaced, with grade beams and an integrated concrete slab.
I have boring logs from the area that are dated 1982, and were used for a similar style building that utilizes piles and grade beams about 100 feet from the project site. The existing borings indicate that the friction piles are used at the existing building. Ideally, I would send a geotech out there for a new set of borings and get their recommendation. However, as per usual, that additional cost is not deemed necessary and was not included in the fee and scope of work. Would there be a significant risk of me missing valuable information if I go through with the design using the existing boring logs and existing building as a reference point? I guess what I'm asking is, what additional information would a new geotech provide me that I do not already have with the boring logs and existing drawings?
I have a general question and wanted someone else's thoughts. I have been tasked with engineering my first driven pile foundation for a 25' high Garage to hold a Vac Truck for sanitary sewer purposes. The garage is 40' x 40', with sub-par existing soils and a high water table. Seems like a pretty straight forward design, was planning to have 9 piles equally spaced, with grade beams and an integrated concrete slab.
I have boring logs from the area that are dated 1982, and were used for a similar style building that utilizes piles and grade beams about 100 feet from the project site. The existing borings indicate that the friction piles are used at the existing building. Ideally, I would send a geotech out there for a new set of borings and get their recommendation. However, as per usual, that additional cost is not deemed necessary and was not included in the fee and scope of work. Would there be a significant risk of me missing valuable information if I go through with the design using the existing boring logs and existing building as a reference point? I guess what I'm asking is, what additional information would a new geotech provide me that I do not already have with the boring logs and existing drawings?





RE: Pile Foundation - Geotech Report Needed?
f-d
ípapß gordo ainÆt no madre flaca!
RE: Pile Foundation - Geotech Report Needed?
A second opinion. Sounds like a very risky design; if even one pile fails the structure has "issues".
Do you have confirmation that the existing structure has performed without problems? Even if so... the user may have been lucky.
www.SlideRuleEra.net
www.VacuumTubeEra.net
RE: Pile Foundation - Geotech Report Needed?
As noted, it is safer to have fresh information, so you can share the blame. Also should get into the habit of sharing your foundation plan with the geotekkie... share more blame.
Dik
RE: Pile Foundation - Geotech Report Needed?
- The soil borings that I have, do not have a soil report and recommendations included with them.
- The existing building is 40' x 70', with a height of ~25'
- The existing building has very similar loading as the proposed building and shows no signs of distress.
- I have not been able to get a hold of a detail or profile that indicates existing pile depth. All I have is pile existing pile size, locations, and a pile cap detail.
- Existing soil borings indicate a water table depth of ~2'-0" below grade
- Existing soil borings indicate ML Soil (USCS) from grade to about 40'-0" below Grade with average blows/ft ~ 23, and SW Soil (USCS) from 40' down to 52' with average blows/ft ~ 72.
RE: Pile Foundation - Geotech Report Needed?
RE: Pile Foundation - Geotech Report Needed?
RE: Pile Foundation - Geotech Report Needed?
Dik
RE: Pile Foundation - Geotech Report Needed?
RE: Pile Foundation - Geotech Report Needed?
RE: Pile Foundation - Geotech Report Needed?
Dik
RE: Pile Foundation - Geotech Report Needed?
I'm sure the risk is very slight- you could probably get away with it 95 times out of 100. But when you start to accumulate jobs like this, that risk turns to guaranteed failure.
If you already have some idea of the soil conditions nearby, I would suggest to your Client that as a compromise on the cost of boring, you put down a few Piezocone (CPTu) test probes. It would put your mind at ease and should be affordable. The Piezocone contractor should provide all interpretation of their probe data, so if it's just the pile design you're doing, you should be able to work on the probe data alone.
All the best,
Mike
RE: Pile Foundation - Geotech Report Needed?
I notice from your handle you are an EIT...what do the senior engineers in your group say? As a general rule, don't do a deep foundation design without SITE SPECIFIC geotechnical info and recommendations!
RE: Pile Foundation - Geotech Report Needed?
[Added] Generally let the geotekkie determine the location and number of testholes.
Dik
RE: Pile Foundation - Geotech Report Needed?
I appreciate all the input, thanks!
RE: Pile Foundation - Geotech Report Needed?
RE: Pile Foundation - Geotech Report Needed?
RE: Pile Foundation - Geotech Report Needed?