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Re: Key Location in cant. retain. walls.

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I also locate the key at the bottom of the wall. But I don't al;ways extend my
wall reinforcement into the key.Sometimes, I bend it horizontally towards the
toe near the bottom of the footing. I put the key there so the trench guy will
have a simple line to follow, same as the wall line.

My question now is: In calculating stability against overturning, where is the
point of rotation? When there is no key, it is usually the bottom of the
footing opposite the backfill.  When there is a key, I think it should be
between the bottom of the footing and the bottom of the key, somewhere......
Right now, I just use the bottom of the footing for simplicity.

In a theoretical analysis, if the key is at the bottom of the toe of the
footing, the point of rotation is at the  face of the footing and key, at the
location of the resultant passive soil pressure resisting sliding(assuming we
neglect friction force under the footing which will not really occur once the
wall and footing starts overturning).

Where do the others locate their overturning point when there is a key?

Ernie Natividad