tolerance for lean of retaining wall

[engn555]

Hi, I am involved in an investigation regarding a leaning retaining wall. I am trying to write a report and am wondering if anyone knows offhand a code based tolerance for angle of lean (ie. what is/is not acceptable), especially in a Canadian context.

Thanks

 

[kslee1000]

I think this is not a code issue, rather an engineering investigation (on original design and strength of the retaining wall)in conjuction with geotechnical analysis is required.

 

[Lion06]

Thre is no acceptablility criteria for lean of a retaining wall that I know of.
I don't know how much the wall needs to actually move to achive the active pressure, but if it is cantilevered retaining wall, it is supposed to move....... again, I don't know how much.

 

[engn555]

It is not an issue of forward movement for the development of active vs passive pressure or anything like that.
The wall is actually rotating or falling over due to the pressure of the soil behind it. Its very obvious to the naked eye; we had it surveyed and its about 8 degrees off a vertical reference line. In other words, an overturning failure. I suspect it was backfilled with the local clay instead of a granular fill.
I was assuming that there must be some kind of tolerance that I could compare it to in my report as even a "properly" designed and constructed retaining wall would be resonably be expected to lean a little bit either backwards or forwards.

Thanks

 

[Lion06]

Then find out what the angle is for development of active pressure for a typical soil and use that.

 

[hokie66]

I cannot remember an actual maximum deflection criteria for retaining walls. Perhaps there should be. But 8 degrees is certainly unacceptable. Is this a cantilever wall or a gravity wall? If cantilevered, the failure could be either rotation or stem failure.

Retaining walls backfilled with clay are very complicated things. If the clay shrinks and swells with moisture change, cracks will collect debris, changing the volume. Where you are the cracks will also collect water and freeze. Thus the movement is often gradual (creep) and can continue to move for years.