====== SOLNL1 ======
===== Description =====
Constitutive law of flow and deformation in porous media for a pipe element 
==== The model ====
Elasto-plastic nonlinear analysis of coupled seepage and compaction in porous media. This law is used for one-dimensional problems
==== Files ====
Prepro: LSONL1.F \\
Lagamine: SOLNL1.F
===== Availability =====
|Plane stress state|YES |
|Plane strain state| YES|
|Axisymmetric state|NO |
|3D state| NO|
|Generalized plane state|NO|
===== Input file =====
==== Parameters defining the type of constitutive law ====
^ Line 1 (2I5, 60A1)^^
|IL|Law number|
|ITYPE| 260|
|COMMENT| Any comment (up to 60 characters) that will be reproduced on the output listing.|
==== Integer parameters ====
^ Line 1 (I5) ^^
|KPERM| 0 $\rightarrow$ loi NISHIDA (K=exp($\alpha e + \beta$)) \\ 1 $\rightarrow$ loi TERZAGMI (K = $\alpha (e-\beta )^{\delta} \cdot (1+e$))|
==== Real parameters ====
^Line 1 (9G10.0)^^
|A| elasticity logarithm modulus|
|C| elastoplasticity logarithm modulus|
|GAMA| = $\gamma$ fluid specific weight|
|$\alpha$| 1st flow parameter|
|$\beta$| 2nd flow parameter|
|$\delta$| 3rd flow parameter|
|$\Omega$| section|
|$e_0$| initial void ratio|
|$\sigma_{p’}$| initial preconsolidation stress|
Note: Y axis is vertical directed from bottom to top.  Gravity same direction, other sense.

===== Stresses =====
==== Number of stresses ====
4
==== Meaning ====
|SIG(1)|axial effective stress|
|SIG(2)| fluid flow in the pipe|
|SIG(3)| fluid flow accumulated as a consequence of the evolution of soil porosity = strain rate|
|SIG(4)| axial total stress |
===== State variables =====
==== Number of state variables ====
4
==== List of state variables ====
|QA(1) |A \\ cross-section|
|QA(2)|e \\ void ratio = $v_v/v_m$|
|QA(3)| $\sigma_{p’r}$\\ yield stress\\ preconsolidation stress|
|QB(4)| yield\\ yield indicator|