Soil nail layout

[Lovi]

Would you design a soil nail system with such a layout( refer to attachment)? if not, why?

equilibrium analyses show its stable. but what happens to all the soil below the nails?

 

[InDepth]

I think what you found out is that the system is globally stable from a slope stability analysis procedure. What you need to consider is if the soil face below the nails is "locally" stable, especially if there is erosion potential. Think of it as if the nails weren't there, would the soil be able to have an angle of repose as shown?

You may want to take a look at FHWA's soil nail manual. Great reference. Not sure what your dimnsions in your graph are, but a 5 ft grid spacing is typical (hopefully you model reflects constructibikity and industry practice).

 

[six06]

You should design it using Snail. It will give you not only the equilibrium analysis/global stability but also the internal stability checks, nail tensile strength, failure envelope, etc.