Soft Modified Cam clay model

The Modified Cam clay model enhanced by the effects of structure in the same way as the structured hypoplastic model, see [4] for the mathematic formulation. Elasticity with constant shear modulus $G$ and Butterfield compression law (linear normal compression lines in the $\ln(1+e)$ vs. $\ln p$ plane) are assumed.

Required parameters:

• Parameter 1 - number of the constitutive model (in this case 1).
• Parameter 2 - bulk modulus of water $K_w$ for undrained analysis using the penalty approach. In drained or consolidation analysis $K_w$ should be set to 0.
• Parameters 3-7 - parameters of the basic Modified Cam clay model ($G$, $M$, $\kappa^*$, $\lambda^*$, $N$)
• Parameters 8-10 - parameters of the extension for structure ($k$, $A$, $s_f$). Basic model without structure is used, if these parameters are not specified.

Therefore, parameters should be specified as follows for the two possibilities

1. No structure: 1, $K_w$, $G$, $M$, $\kappa^*$, $\lambda^*$, $N$
2. Structure: 1, $K_w$, $G$, $M$, $\kappa^*$, $\lambda^*$, $N$, $k$, $A$, $s_f$

Required state variables:

For all cases 5 state variables required:

• State v. 1 - void ratio $e$.
• State v. 2 - sensitivity $s$.
• State v. 3 - Excess pore pressure $u$ for undrained analysis (compression positive sign convention).
• State v. 4 - Suggested size of the first time substep (for calculation controll).
• State v. 5 - Number of evaluation of the constitutive model in one global time step (for postprocessing only).

State v. 2 ($s$) automatically initialised to 1 if model without structure is used or if its initial value is 0.

Typical parameters:

Table 3: Typical parameters of the Soft Modified Cam clay model

	$G$	$M$	$\kappa^*$	$\lambda^*$	$N$	$k$	$A$	$s_f$
Pisa clay [4]	1000 kPa	0.85	0.02	0.14	1.56	0.4	0.1	1

Example input file and initialisation file for the FE program Abaqus$^{TM}$.
Example input file for the FE program Tochnog Professional.