Soil properties for short-term stability through SLIDE

[dtsk]

Hi all,

I am assessing the short-term stability of a road embankment.

To model short-term stability behavior, i have used the Undrained Shear Strength for cohesive soils.

How would you model a non-cohesive layer in Slide software? Would i be correct in simply using the Mohr-Coulomb c':0 , phi : 30 deg?

Thanks for your help!

 

[GeoPaveTraffic]

You would be correct using a C=0 and Phi = an appropriate angle for free draining materials.

Mike Lambert

 

[Okiryu]

If you have SPT data, you can use that data to get phi: there are several correlations between SPT N-value, normal stress and friction angle for granular soils.

 

[dtsk]

Great, thanks Mike & Okiryu.

 

[HENRYZAU]

Comments on undrained strength for clay:
Depending on whether it's a cut slope or fill slope, and whether it's NC, lightly OC or heavily OC, and the definition of short term (should be so short that less than 10% excess pore pressure is dissipated), using undrained strength for clay is not always safe.

For granular materials yes c'=0 and phi' are correct unless you are facing saturated fine sand in an earthquake event.