[MPL] Documentation for EmbeddedFracturePermeability

Documentation/ProjectFile/properties/property/EmbeddedFracturePermeability/c_EmbeddedFracturePermeability.md

+\copydoc MaterialPropertyLib::EmbeddedFracturePermeability

Documentation/ProjectFile/properties/property/EmbeddedFracturePermeability/t_fracture_normal.md

+Optional Parameter fracture_normal. Defines the normal vector of the fracture plane via its three components. If not specified, the fracture normal vector is calculated as the direction of the third principal stress vector.

Documentation/ProjectFile/properties/property/EmbeddedFracturePermeability/t_initial_aperture.md

+The inital aperture.

Documentation/ProjectFile/properties/property/EmbeddedFracturePermeability/t_intrinsic_permeability.md

+The permeability of the undisturbed material.

Documentation/ProjectFile/properties/property/EmbeddedFracturePermeability/t_mean_frac_distance.md

+The mean distance between neighboring fractures.

Documentation/ProjectFile/properties/property/EmbeddedFracturePermeability/t_threshold_strain.md

+Threshold strain, which has to be exceeded to create additional permeability due to fracture opening.

Documentation/bibliography/other.bib

@@ -175,3 +175,26 @@
   year={2011},
   publisher={Elsevier}
 }
+
+@article{alonso2006mechanisms,
+  title={Mechanisms of gas transport in clay barriers},
+  author={Alonso, EE and Olivella, S and Arnedo, Diego},
+  journal={Journal of Iberian Geology},
+  volume={32},
+  number={2},
+  pages={175--196},
+  year={2006},
+  publisher={Citeseer}
+}
+
+@article{olivella2008gas,
+author = {Olivella, S. and Alonso, E. E.},
+title = {Gas flow through clay barriers},
+journal = {G{\'e}otechnique},
+volume = {58},
+number = {3},
+pages = {157-176},
+year = {2008},
+doi = {10.1680/geot.2008.58.3.157},
+URL = {https://doi.org/10.1680/geot.2008.58.3.157}
+}

MaterialLib/MPL/Properties/EmbeddedFracturePermeability.h

@@ -19,6 +19,31 @@ namespace MaterialPropertyLib
  * \brief Permeability model as proposed by Olivella&Alonso
  * \details This property must be a medium property, it
  * computes the permeability in dependence of the strain
+ *
+ *  The model was proposed
+ *  in \cite alonso2006mechanisms and it was further investigated
+ *  in \cite olivella2008gas .
+ *
+ *   The model takes the form of
+ *  \f[ \mathbf{k} = k_\text{m} \mathbf{I} + \frac{b}{a} \left( \frac{b^2}{12}
+ *      - k_\text{m} \right) \left( \mathbf{I} - \mathbf{M} \right)
+ *  \f]
+ *  with
+ *  \f[ \mathbf{M} = \vec{n} \otimes \vec{n} \f]
+ *  and
+ *  \f[ b = b_0 + \Delta b \\
+ *      \Delta b = a \langle \varepsilon_\text{n}- \varepsilon_0 \rangle
+ *  \f]
+ *   where
+ *   <table>
+ *   <tr><td>\f$ k_\text{m} \f$  <td> permeability of undisturbed material
+ *   <tr><td>\f$ b \f$  <td> fracture aperture
+ *   <tr><td>\f$ b_0 \f$  <td> initial aperture
+ *   <tr><td>\f$ a \f$  <td> mean fracture distance
+ *   <tr><td>\f$ \vec{n} \f$  <td> fracture normal vector
+ *   <tr><td>\f$ \varepsilon_n \f$  <td> strain in fracture normal direction
+ *   <tr><td>\f$ \varepsilon_0 \f$  <td> threshold strain
+ * </table>
  */
 template <int DisplacementDim>
 class EmbeddedFracturePermeability final : public Property