GEOSTRATA, 2015, May/June, 10-11

Readers Agree with Macnab’s Common-Sense Approach Letters

 

letters

 

I just read Alan Macnab’s “As I See It” commentary in the January/February 2015 issue of GEOSTRATA and passed it around to the other engineers in our small office. They had the same complaint I had. The article was too short. But it was right on the money.

I am a deep foundation contractor specializing in pile driving/drilling/ augering with particular interest in sheeting, shoring, and underpinning systems for over 40 years. His Earth Retention Systems Handbook has been read and re-read by our engineers for a dozen years.

We spend too much time lately explaining the obvious to engineers who have a “new idea” about how structural and geotechnical designs should combine. Thanks for the fine article.

George M. Morris, PE President, Macro Enterprises, Ltd. Massapequa, NY macroent@optonline.net 

I really enjoyed reading Alan Macnab’s “As I See It” commentary in the January/ February GEOSTRATA. I am only 20 years into my career, but have noticed many of the same things. While computer tools are great, too many young engineers don’t understand that they are just tools; it’s our mind that solves the problem. When my mentor Fred Brown retired, he was gracious enough to pass on his “Secret Book.” He had recorded all of the rules-of-thumb and lessons he learned from observations made during his 40-year career. Things they would never put in a book now for fear of being sued… but they still work if you know how to apply them.

Alan’s commentary is a great reminder that we stand on the shoulders of those who came before us. The timing of this article was great with the tribute to my firm’s founders; we still use much of the equipment and methods that they developed during their career. Thanks for publishing the reminder of who we are.

Stafford Glashan, PE, M.ASCE Shannon & Wilson, Inc., Anchorage, AK SJG@shanwil.com

I thank Alan Macnab for his “As I See It” commentary in the January/February 2015 issue of GEOSTRATA. As always, sage words from someone who has experienced a lot. We need to remember that common sense is a more valuable tool than numerical modeling sometimes.

Allen W Cadden, PE, D.GE, M.ASCE President, ASCE Geo-Institute acadden@schnabel-eng.com 

It was refreshing to read the “As I See It” commentary by Alan Macnab in the January/February 2015 issue of GEOSTRATA. Alan and I entered the industry at the same time. My first employer was the George Hyman Construction Company of Washington, DC. Frustrated by its subcontractor’s performance, Hyman decided to develop a self-perform capability in excavation support and foundation construction. I was fortunate to be hired and mentored by Hank Kramer, an alumnus of the old Spencer, White and Prentis, and Harry Schnabel. Washington DC is a great city for those who love shoring and foundation design and construction. Due to building height restrictions, buildings are forced ever deeper into the ground to provide parking and other functions.

Alan’s comments regarding the loss of the observational method in shoring and foundation design hits the nail on the head. Hands-on experience with the ground you are excavating is invaluable in predicting the soils’ behavior and is far more reliable than a computer-generated soil characterization. In addition, the experience and knowledge of the sand hogs and pile drivers that actually perform the work should be incorporated into any shoring or foundation design.

Alan’s comments on the design, inspection, and construction of drilled shafts reminded me of an interesting project. It required that we request a code modification to found several small-diameter drilled shafts on rock rated at 50 t/sf. When we reached what we assumed was competent rock, we requested inspection and approval. A city inspector arrived at the project with a ball-peen hammer, pinged the rock a few times, and declared it 50 t/sf.

One additional technique that has apparently faded from use is the hand dug underpinning pier. These 3 ft x 4 ft pits were used extensively in DC to support adjacent structures and extended as deep as 40 ft.

Regarding the thickness of lagging, I agree with Alan that timber must have lost significant strength. I was recently provided with a design that called for double, 6-in. thick boards for a 9-ft span between soldier beams.

Alan G. Hobelman, PE Beverly Hills, CA ahobelman@roadrunner.com

Thanks for the Poetry

Just a quick note to thank Mary Nodine for her GeoPoem, “Soil of My Dreams,” in the March/April 2015 issue. I’m not normally one for much poetry, but I have to admit that Mary’s contribution is one that I always look for and enjoy — her creative wordsmithing often makes me laugh. Thanks again for bringing smiles to many of us!

Kord Wissmann, PhD, PE, D.GE Geopier Foundation Company, Davidson, NC kwissmann@geopier.com

 

GEOSTRATA welcomes letters to the editor. Some letters may be edited to suit style and space guidelines. Please send them to us at geostrata@asce.org