retaining wall with keys 1

[SEmil]

How to design the retaining wall with keys?
- should the soil active pressure and surcharge load below footing to bottom of key be considered?
- has anyone designed the footing with 2 keys? if so, can i use the soil passive pressure at both keys for sliding?

 

[escrowe]

A detailed drawing would help.
Is this a flood wall?

Generally active pressures to not apply to keys;
keys typically resist sliding,
but may be modified to increase resistance to overturning and increase the length of seepage paths.

Multiple keys may have overlapping zones of horizontal influence,
and the passive resistance should be calculated accordingly.

 

[PEinc]

Just a thought, but if the wall is so big that it needs multiple shear keys, perhaps it is the wrong type of wall. Maybe a permanently anchored wall (tiedback or soil nailed) is more appropriate. Or possibly the shear keys could be replaced by tieback anchors or piles through the footing.

 

[hokie66]

I have never used 2 keys on a wall. Would not making a single key deeper be more practical?

 

[VoyageofDiscovery]

I have seen keys over the years, but have yet to really be convinced of their general effectiveness. If the soil slip circle in front of the key is weaker that the ultimate passive resistance then relying on it is highly suspect. My thought are to always consult a geotechnical engineer in these cases.

 

[MIBridgeEng]

I don't design in California, but sections 5.6.3, 5.6.4.1, and 5.6.4.2 in the Caltrans 2003 Bridge Design Specifications does talk about keys and when to apply active and passive pressures to the key.

http://www.dot.ca.gov/hq/esc/techpu...ridge-design-specifications/page/section5.pdf