Why 5% strength of reinforcement? 1

[smaller]

Does any one know why we use 5% strength of reinforcement, not 1% or 3% strength of reinforcement to determine the internal stability of reinforced slope?
Please kindly help me.

 

[MSEMan]

Generally we're not using 5% strenght, we're using the strength at 5% strain. The reason is based on the strain compatability of the system. Since a granular soil will fail at 5% strain, that's also the mobilization limit for the geosynthetic. It makes some sense since most geosynthetics reach their peak strength at something around 11% strain, the increase in strength between 5 and 11% can only be mobilized post soil failure.

Some recent strain based methods, K-stiffness for example, are promoting using the secant modulus at 2-3% strain.

 

[smaller]

Thank you so much.
you are really a MSEman. ha ha
Good day!