Disrupted shear failure plane of soil 1

[WARose]

I have a situation where I have to consider one possible mode of failure for a foundation as the shear failure plane. (I.e. a retaining wall key.)

However, the "plane" crosses a patch of ground that was disturbed some years back. (20 to be precise.) Basically a hole was made.....and it was re-filled. But not compacted. (The other soil in the area is undisturbed, and well compacted.)

What should I consider here as far as the failure plane goes? Just disregard the part that runs through where the hole was? Thanks.

 

[r13]

Do you have soil engineer work with you? For large area, maybe take a few samples is warranted. For small area, can't you just replace with competent fill?

 

[WARose]

Do you have soil engineer work with you?

Not currently. I have enough geotechnical info on the original drawings to know certain things though.

For large area, maybe take a few samples is warranted. For small area, can't you just replace with competent fill?

Before I go in that direction.....I'm trying to get some feedback on my original question. (Not just for this but for future reference.)

 

[r13]

It's never been a good idea to place foundation on questionable soil, I don't think you should consider to bridge over the potential weak spot, the thought can backfire.

 

[oldestguy]

In my experience occasionally we run across some changes in the site that were not anticipated. So we deal with that at the time. For a likely limited area, plan to call for help if you REALLY need it. Otherwise you can always replace the stuff with better material and compact. A lot of improvement in those years likely took place. Surprisingly what even a year can do.

 

[Ron]

OG is right as usual. 20 years is a long time for equilibration of soil after placement. Likely achieves similar to surrounding soil at this point. Further, soil conditions are almost NEVER homogeneous and isotropic. We only assume such and live with it.

 

[WARose]

Thanks oldestguy.