fill on slope

[longisland]

hi,
I need to design an access road to a hill site. The natural is roughly 20 degree;
the approach road gradient has to be reduced to 10 degree.
I can't cut the whole slope down due to site constraint; I plan to reduce the grade by extending the approach up to the mid section of the slope & then trim down the rest of the slope. what is the best approach to construct the approach?
I've thought of constructing a ramp structure or using reinforced earth.
The structure is costly but I'm not confortable filling on existing slope. Any other suggestions?
The existing ground is sandy silt; I'm worry the whole section of the approach may slide if I were to fill earth ontop.

 

[Focht3]

It sounds like a geotextile-reinforced soil mass is your best solution. Reinforced Earth, Tensar geogrids don't do well with silts. Use a spun-bonded, needle-punched polypropylene geotextile product - will act as both a reinforcement and a filter. The geotextile will become the (temporary) face of your slopes. You will need to cover the geotextile to protect it from UV damage, vandalism, etc. I'm not sure what will happen when your site freezes...

Check with your local Tensar distributor; they should know what's available and provide you with samples and design guidelines. And perhaps a computer program for design.