Temporary Retaining Wall

[ataman]

Hi

I have a situation with a house being constructed on a hillside. The front foundation wall will be 10 feet above the ground and we will be filling behind this wall. The fill is not to be compacted and will serve as the formwork for the floor slab which will restrain the top of the wall. My question is what guidelines should I use in a situation where the foundation wall will function as a retaining wall only temporarily until the floor slab is in place?

I was thinking of reducing the unit weight of the fill to probably 90lbs/ft3, keeping the friction angle at 30-32 degrees but lowering my factor of safety for Overturning to 1.3. Does this sound reasonable?

Thanks

 

[casimmons]

Is the first floor a ground supported slab? If so, you should probably compact the fill so that it can provide adequate slab support.

Also, I'm sure you realize that the wall will have lateral pressure on it after the floor slab is in place, and that those at-rest pressures will be higher than the active pressures for the retaining wall.

You need to provide some more information about the soil type, but the low unit weight and relatively high friction angle don't seem right for uncompacted soil.

 

[civilperson]

Bad idea, design for compacted fill behind your wall. This may never happen, but if it does, the repair costs will be many hundreds times greater than the initial difference in cost.

 

[oldestguy]

Civilperson is correct.

If you "take a chance" with a conventional poured concrete wall that has "set up" some, it may fail. Who will take that blame?

However, I have seen this done (no design)for a wall about12 feet high. The darn thing worked. 5 years later it still is there, but I didn't get involved with it.

Through the years, I have seen may dumb things that "got by", so who is to know yes or no for sure that your plan won't work. It all depends on how much of a gambler you are, I suppose.