Foundation Settlement and Rail Traffic

[phamENG]

I'm curious to see if anyone has considered this in any detail before. A frequently used rail line (4-8 trains/day) runs along the back side of a neighborhood. Speeds are fairly low (only a few miles from the end of line), but residents complain about significant vibrations every time one comes by (glass vibrating, nick-nacks shaking on shelves, that sort of thing). These are freight trains.

Has anyone found this to be a root cause or significant contributing cause for excessive foundation settlement? Soils are mostly soft sandy clays - a region of WOH material about 20 feet down. Does it seem plausible?

 

[oldestguy]

This old guy has been retired a few yes now after some 50 or more years of practice in geotech field. While the subject seems to come up once in a while, but no finger pointing to this as a cause of a nearby problem that has been worked on, etc. My old memory says one case of foundation settlement of a railroad bridge over a roadway was blamed in part on the vibrations. I'd "guess" in most cases any settlement would occur early on in the life of the nearby foundation. However,I have seen several cases where machines impacting with a lot of shaking to the ground has affected not only the machine but nearby places. Loose sands most likely to see some effect.

 

[phamENG]

Thanks, oldestguy. There may be some loose sands down there...they gave me boring logs, but they were done by a contract driller with no geotechnical supervision. No samples were retained/tested - just blow counts and a qualitative description of the color and soil type. It may just be lots of uncontrolled fill over an old swamp - we have a lot of those around here.

 

[SlideRuleEra]

phamENG - Agree with OG. Our rail loops for coal unloading at generating stations are above deep "swampy" soil, but we have not not had significant settlement of nearby slab-on-grade buildings / equipment. The railway bed / tracks themselves settle constantly (requiring routine reestablishment of rail elevation), but not adjacent structures. I'm sure that it helps for the structures to have been designed with conservative allowable soil bearing pressure.

http://www.SlideRuleEra.net

 

[GeoPaveTraffic]

I've never seen a settlement problem actually linked to rail vibrations. Most of the issues in the houses are probably more due to noise/sound induced vibration than to actual ground vibration. This would be especially true near the end of the line with slow speeds and the car couplers banging together.

Lastly, not that it really matters, I would say that a line with 4 to 8 trains per day is used, but not frequently. A busy line can have over 30 trains per day.

Mike Lambert

 

[phamENG]

Thanks guys. And fair point, GeoPaveTraffic. I'm sure we'd see that many if they could fit the cars in at the terminal.

I hadn't dealt with a case this close to a line before, so I'd never thought of it. Now I know that it's not a likely culprit for foundation problems. The china falling off the shelves may be a different story, though.