19th century retaining wall engineering 2

[a7x1984]

The attached photo is of a 50-foot tall or so stone retaining wall adjacent to the northern portal of the Howard Street CSX tunnel in Baltimore, MD. The tunnel was constructed in the last decade of the 19th century, so I assumed that this retaining wall is dated the same, as the stone type is the same as the portal arches it connects to.

Does anybody have an idea how these were engineered at that time? It's un-battered height is impressive. It seems it couldn't be a mass wall.

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[PEinc]

Why couldn't the rear face of the wall be battered?

http://www.PeirceEngineering.com

 

[concretemasonry]

No question about battering the rear face on that type of wall. The extra thickness is not really needed as much for the upper portions.

Many of those structures were built according to personal and perceived standards and not actually engineered.

A few centuries earlier, you (contractor) would get a hand or arm cut off for failure or be put to death if someone died. The 19th centuries was before real proven designs/standards and proven practices were were followed, although some engineers tried to send samples to labs and compare to any existing standards and try to instrument existing structures and compare using the design drawings.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[emmgjld]

Society always seems to perceive that the last century (to say nothing of the 5 centuries back) are close to primitive. My father (deceased) made a point of teaching me that as engineers, we often spend a lot of time proving the worth of what has gone on in the past. Yes, you can now provide calculations and predictions. But are we really better builders than our ancestors?

"Does anybody have an idea how these were engineered at that time?"
By experience. They worked out the issues, were not afraid to try and were not excessively 'Risk Adverse'. Sure, they truly avoided failure but did not put their heads in the sand.

Using others experience was also a major part. It is interesting to note the number of 'monuments' of the past are the ones which where successful. The failures failed and were replaced. Due to a presentation my Father gave for 'design types' in Colorado Springs in, I believe 1966, We researched older book for repairs (& methods) of old to ancient structures. We also went through, recent photographs to pick out obviously repaired or modified areas. The methods of underpinning, for instance, before 1400 AD look fairly modern, to include diving bells.

The issues of drainage for structure stability, for instance' were fairly well understood thousands of years ago. I look at the the recent construction sponsored by the Colorado DOT and they could take some serious lessons from the Romans. A wealth of computer programs has not produced the vast majority of the world's Civil Works.

 

[bridgebuster]

Attached is a standard drawing issued in 1913 by the Bronx (NY) Boro President's Office for construction of stone retaining walls.

If you go to

http://www.books.google.com

you can download numerous books from the late 1800's/early 1900's that explain gravity wall design. Stability theory was understood back then.

I like emmgjld said:
"By experience. They worked out the issues, were not afraid to try and were not excessively 'Risk Adverse'. Sure, they truly avoided failure but did not put their heads in the sand."

Those guys had "stones", not like today where there are too many engineers who are afraid to think and argue their convictions. They prefer to take the easy out, "...but the code says..." or "...that pile has a factor of safety of 6, you can't lower it to 5".

 

[a7x1984]

bridgebuster: excellent attachment. that is what I was looking for.

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[bridgebuster]

You're welcome

 

[aeoliantexan]

I have a copy of "the Civil Engineer's Pocket-Book by Trautwine, 20th Edition, 1918. The first Edition was 1872. The intoduction to the retaining wall section says, "A retaining -wall is one for sustaining the pressure of earth, sand, or any other filling or backing, deposited behind it after it is built, in distinction to a face-wall, which is a simlilar structure for preventing the fall of earth which is in its undisturbed natural position, but in which a vert or inclined face has been excavated. The earth is then in so consolidated a condition as to exert little or no lateral pres, and therefore may generally be thinner than a retaining one."

I have seen vertical masonry walls 15 feet tall and maybe 2 feet thick that obviously depended on the soil to support itself. A broken water main would destroy such a wall, of course.

At any rate, Trautwine gives rules for base width to height ratios for "retaining-walls" that start at 0.35 for loosely-dumped backfill against a wall of cut stone or first-class ranged rubble, in mortar, 0.50 for well-scabbled dry rubble.

"For compacted backfill, the thickness may be reduced, but no rule can be given for this."

He gives various other rules and some theoretical analysis. He names other authorities and states clearly where he differs with them.

The section is 11 pages.
If you have an address, I'll send you a copy

 

[a7x1984]

Awesome, aeol.


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[a7x1984]

aeol: post an FTP address link, if you could.

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