Advanced Soil L7

This is 1D elasto-plasticity

The boundary of the elastic region.

The state of failure is the final yield locus which no longer expands/contracts

The yield locus becmes a yield surface

Elastic behaviour when this is < 0

Impossible stress when > 0

A surface which defines the direction of plastic straining on yield surface

Flow rule: the vector of total plastic strain normal to plastic potential surface

Associated plasticity : if YS and PS coincide, where F=P

Elastic. On the yield surface, (Roscoe, Hvorslev, or tension failure), is elasto-plastic

Strain-hardening shown by expansion of the envelope

The envelope contracts in on the 'dry' side, strain-softening

deviatoric plane is circular

 Adopt ellipse

Circular

Determining total vol strain:

v= N-λlnp'

differentiating: dv/dp' = -λ/p'

Determining elastic: v= vk-klnp', dv/dp' = -k/p'

so the sum -k/v*dp'/p + λ/v*dp'/p' = de,_pvol

It overpredicts the strength in deviatoric plane outside triaxial compression 

solution: Use Mohr-Columb in expression

It overpredicts strength of the highly overconsolidated clay

Introduce Hvorslev and ensure flow rule at critical state

Overpredicts side of elastic region - couple MCC with a small strain stiffness model