Slope Acceptability

[GoldDredger]

I've got an access road looping back on itself on a moderately sloped site.

There is a vertical separation between the two roads as they converge from 0 to about 8 feet maximum. I am able to maintain a consistent slope of 1:1.33 (V:H)across this vertical separation. I'm proposing a non structural concrete cap of 4-inches atop the slope to prevent erosion.

I am trying to save the cost of a retaining wall, however I've always kept 1:3 (V:H) as save rule of thumb for slope stability, and this is much steeper.

Both roadways will be installed in cut conditions up to 8-feet depth, and the geotechnical borings are 20-feet deep. The soil strata is primarily clayey sand.

The roadway load is expected to be light duty primarily, however must also be able to handle fire truck (H-20) loading.

Any suggestions on how to perform the stability analysis for this?

 

[fattdad]

get soil strength, get topography, use a surcharge pressure for traffic loading and make a slope stability model.

f-d

¡papá gordo ain’t no madre flaca!

 

[dgillette]

And, as fattdad and I have discussed lately, beware of softening of the clayey stuff with time. A low 1.33:1 H:V slope may be just fine in the short term, but then become unstable with time as cohesion (real, or apparent due to capillarity) is essentially lost. It may depend on how clayey the clayey sand is.

From here on, I will defer to him and others that have more direct experience with it than I do.

 

[brandonbw]

The Geo Engineer should be telling you if it's okay to run the slope at that grade, possibly removing and replacing the soil during grading?

B+W Engineering and Design
Los Angeles Civil and Structural Engineering

http://bwengr.com