Lateral Soil Pressure on Wall w/Soil Nails 1

[SteveGregory]

I am looking at designing a basement wall that is tied back with soil nails or helical anchors. The entire wall from top to bottom will be tied back. The site is very steep, about 30 degrees. The building will have wood framing that does not have the capacity to restrain the forces at the top of the wall and I have concerns about the foundation restraining the bottom of the wall without sliding.

Under normal conditions, I would use an "at rest" pressure that would be retrained by the floor diaphragm and the foundation. So what type of soils information should I request from a geotechnical engineer?? And what type of a pressure profile should I use to develop the proper loads for the helical anchors and the concrete wall design???

Looking in my Bowles textbook, I may need to use a pressure diagram similar to a single-wall braced cofferdam. I don't have a water table or a surcharge. The soil is predominately a clay type (not shrink/swell type). Comments???

 

[DaveAtkins]

I think you are correct to use the Terzaghi method, since this is like a braced cofferdam. I think the pressure will be more like an at rest pressure, since the wall will move a little bit to engage the soil anchors.

If you tell the geotechnical engineer what you are proposing, he/she should be able to give you the soil parameters you need.

DaveAtkins

 

[SteveGregory]

I'm a little slow with my response. Thanks, Dave!