Is a new Geotech Investigation needed.
Is a new Geotech Investigation needed.
(OP)
We have a couple of 30-year transformers with pads that are 4.5' deep, 10'long and x 20' wide. We are replacing the transformers, but want to reuse the pads. The new transformers are about 20% heavier, and has its center or gravity shifted off the center-line in the short direction of the pad. We calculated the max pressure on one side of the foundation doubles from the increased load and eccentricity.
Back when the earthwork occurred, we know the soils were tested, and were a well controlled engineered fill. We have an old document that prescribed an allowable bearing of 8.5 KSF (for the whole site). The underlying soils are deep highly Compacted medium sand.
I'd appreciate any input on this you have to offer; do those numbers seem unreasonable for compacted sand, does getting a geotech in on this seem reasonable; drilling holes near these devices is terrifying for us, is there an other means to establish the grounds adequacy without drilling?
Thanks.
Back when the earthwork occurred, we know the soils were tested, and were a well controlled engineered fill. We have an old document that prescribed an allowable bearing of 8.5 KSF (for the whole site). The underlying soils are deep highly Compacted medium sand.
I'd appreciate any input on this you have to offer; do those numbers seem unreasonable for compacted sand, does getting a geotech in on this seem reasonable; drilling holes near these devices is terrifying for us, is there an other means to establish the grounds adequacy without drilling?
Thanks.





RE: Is a new Geotech Investigation needed.
Also consider having a new structural engineer evaluate the structural adequacy of the existing pad, once you have the new soils report.
RE: Is a new Geotech Investigation needed.
RE: Is a new Geotech Investigation needed.
RE: Is a new Geotech Investigation needed.
Do you know, if this site has high ground water table? Have you tried supporting equipment on saturated SAND, when imposed bearing pressure is 8.5 ksf? I wouldn't put my stamp on it.
If cost of a small soils report is a concern, compare that to undepinning and replacing damaged equipments!
RE: Is a new Geotech Investigation needed.
I was recently thrown under the bus when my boss insisted on new soil borings, at the 11th hour, for two additions we were putting on buildings previously designed by our firm 20 & 30 years ago. Soil reports were long gone due to records retention, but I had back calculated values from each building and they were totally in sync.
We finalized our design with presumptive Code bearing capacities, issued the drawings, and then revised them during bidding when the new soils report pretty much concurred with the values I had originally used.
The Owner's PM had me thrown off of the job. I was still doing the work behind the scenes - but never in direct communication with him.
Not being an Owner I can't fully appreciate my boss's caution maybe due to liability concerns or whatever.
Engineering certainly isn't the profession it once was.
gjc
RE: Is a new Geotech Investigation needed.
RE: Is a new Geotech Investigation needed.
The pad is pretty massive (weight-wise). However, you should probably do a check on any new vibration amplitudes that might be developed and confirm that they are acceptable.
RE: Is a new Geotech Investigation needed.
RE: Is a new Geotech Investigation needed.
RE: Is a new Geotech Investigation needed.
f-d
¡papá gordo ain't no madre flaca!
RE: Is a new Geotech Investigation needed.