Lateral pressures due to steep slope surcharge 3

[inaz]

We are constructing a steep reinforced slope (1:1) above a vertical concrete retaining wall. I'm having a difficult time determining the additional lateral pressure on the wall due to the steep slope. Rankine, Coulomb, or log-spiral do not work for slope angles greater than phi.

I'd like to determine the additional surcharge load by itself, so I can just add it to the load directly behind the wall using different wall backfill materials.

Please help me find a good reference for this condition. Thank you.

 

[PEinc]

Can you analyze the wall as having flat ground behind but with a variable surcharge load due to the increasing depth of sloped overburden?

 

[inaz]

PEinc ~ I like that thought, I'll explore that. Thanks

 

[henders1]

British Steel Piling Handbook gives guidance on this. Assume horizontal surface, then increase pressures by 5% for each 5 degrees of inclination above the horizontal. Not sure where you are based, but in the UK, the Piling Handbook would be considered to be a sound reference text

 

[oldestguy]

I dug out some material from my old files on this and see that Osterberg in 1962 summarized five different papers on the subject and mentioned the Newmark charts as well as charts by Fadum. These papers dealt with vertical pressures at various places under and nearby embankment loadings of various configurations.

If you have access to or can get the Facum charts via BigH or others, look for this:

Fadum, Ralph "Influence Values for Estimating Stesses in Elastic Foundations" from Proceedings of 2nd Int. Conf, S.M. and Foundation Engineering,Vol. III, pp. 77-84.

Once you have the vertical pressure, factor it to the horizontal by the ususal methods.

Also, my old NAVFAC DM-7.1, on page 166, Figure 2 has formulas for figuring what you have as both horizontal and vertial stresses at points below and off to the side for different embankments configurations.

You may be able to get this from the current NAFAC documents as posted on the Internet. They call your situation Terrace loading. The figure is entitled "Formulas for Stresses in Semi-infinite Elastic foundations". I suspect these are Fadum's charts.

The last I looked at NAVFAC material on the Internet site they had most of the old material from the old book.

 

[oldestguy]

Well as I looked today at their site, here is a link that may help:

http://www.ce.washington.edu/~geotech/courses/cee523/manuals/NAVFAC72.pdf

I did not find the charts I mentioned above, but this Figure 11, with the stress distruibution for line loads, ought to work. Divide your earth load into a series of strips and add up the distributions that you get from these, plus your horizontal earth surface pressures.