Soil Boring Layout by SER

[Boiler106]

as structural engineers, we are routinely asked to layout soil borings by our architect clients, which are passed along to the geotech.

while it might be common, to me, it has never made much sense. ive always contended that the geotech needs to develop opinions based on the borings and should be responsible for placement, provided he has access to the building layout, a description and estimated column loads.

does anyone else see it any other way? should the SER be responsible for this from your perspective?

 

[oldestguy]

Having set up field investigations for thousands of jobs, I sometimes have had to deal with what was already laid out and performed. Many of those done before I received the data were OK, but a larger portion left me with having to make recommendations that might have been more economical if I had charge of the field work to begin with, or even suggested more field work or lab work.. So you can see my answer, Those that have to make the most suitable and economical recommendations for foundations should be involved from the beginning.

 

[DETstru]

I always defer to the geotech to lay out the borings. They know how many and where to locate them.

That being said, you should provide the geotech with any information you have on the site (anecdotal and tangible info) along with a preliminary foundation plan or at least the column locations. If you can give max/average column loads, even better.

 

[ACE58]

Actually, I think it's beneficial to handle it this way. Frequently the soils engineer is hired when the building drawings are in the schematic or design development phases - without actual framing plans, column layouts or loadings called out on the plans. By this time I've usually visualized a concept of how the structure will be framed & can "guesstimate" the uniform & point loads that will be present. Knowing where the most significant loads will be, I can indicate where I think that soil borings should be taken & distribute them across the building pad in the most economical way. Sometimes this is as simple as placing some redmarks on a print of the site plan , scanning it & sending to the soils engineer. The soils engineer is advised that if they encounter "questionable" soil on site that could affect the building, they are to contact the EOR to determine if additional borings are necessary. If conditions warrant it, sometimes the building is repositioned to minimize corrective measures to support the building.

 

[slickdeals]

IBC is pretty clear about this. Section 1802.4.1 places the responsibility on the "registered design professional", who in this case is the Geotechnical engineer.

 

[cvg]

for a lot of bridge, dams and other large civil infrastucture it is generally mandatory that the borings be located on centerline or at the actual pier locations. It is then required that the designer set either a baseline or stake out the recommended locations of the borings based on input from the geotech. I usually also have the driller set stakes and then send out the survey crew to locate the actual boring location which is often not where it was originally planned. As far as the number of borings, trenches or depths, that minimum number is determined entirely by the geotech. None of this requires any architect input...

 

[thaidavid40]

This doesn't have to be an either/or proposition. We routinely send preliminary boring locations along to the geotechnical engineer, along with project data, for his comment. Good comments are worked into the final plan from us (the S.E.R.).
Dave

Thaidavid

 

[sticksandtriangles]

I just had to do this for the first time myself, except the architect was sending out a request for proposal for geotech services.
What do you guys typically do if a geotech is not even on board yet and the arch is having you look at proposed boring locations?

 

[KootK]

I always refer back to this thread with some great work by JAE et al: Link. It's usually enough to make me the smartest guy in the room unless that room contains a seasoned geotech.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[GeoPaveTraffic]

In a perfect world the boring locations would be determined based on a discussion between the structural engineer, the site civil engineer, and the geotechnical engineer. But as we all know, we live and work in a very imperfect world. If the number of borings and their locations are picked by the structural engineer, he/she should at least ask the geotechnical engineer if the number and locations look about right. Many times there are geologic reasons that borings should be moved around.

Mike Lambert

 

[Boiler106]

If i provide column loads, building layout and a description, what do I gain by providing soil boring locations?

I'm not deriving a professional opinion about the soils. Seems like it's adding to my liability.

 

[sticksandtriangles]

Thanks for the link Koot. I will keep this stickied for future requests.

 

[slickdeals]

A geotech provided this to me a long time ago. Similar to what JAE has provided, but more in depth.

 

[kmart30]

I've been on both sides and the project budget is usually always a huge factor. Either way a good basis for depths of your borings will be based on the width of your footings and/or how many stories are going up. Quantity will be based on the typical geology at the project location and the minimum amount of borings a geotech will need to feel comfortable giving you bearing capacities and settlement estimates.

A good reference would be your states DOT soil exploration guidelines. It will give you minimum boring requirements for different types of structures and other information. Its usually overkill for the private sector but you can at least have a reference to follow.