FluidSolidPorousMaterial couples the responses of two phases: fluid and solid. The fluid phase response is only volumetric and linear elastic. The solid phase can be any NDMaterial. This material is developed to simulate the response of saturated porous media under fully undrained condition.
The following information may be extracted for this material at given integration point, using the OpenSees Element Recorder facility (McKenna and Fenves 2001): "stress", "strain", "tangent", or "pressure". The "pressure" option records excess pore pressure and excess pore pressure ratio at a given material integration point.
|nDMaterial FluidSolidPorousMaterial $tag $nd $soilMatTag $combinedBulkModul <$pa=101>|
|$Tag||A positive integer uniquely identifying the element among all elements|
|$nd||Number of dimensions, 2 for plane-strain, and 3 for general 3D analysis.|
|$soilMatTag||The material number for the solid phase material (previously defined).|
|$combinBulkModul||Combined undrained bulk modulus Bc relating changes in pore pressure and volumetric strain, may be approximated by:
Bc ≈ Bf /n
where Bf is the bulk modulus of fluid phase (2.2x106 kPa (or 3.191x105 psi) for water), and n the initial porosity.
|$pa||Optional atmospheric pressure for normalization (typically 101 kPa in SI units, or 14.65 psi in English units)|
1. Buoyant unit weight (total unit weight - fluid unit weight) should be used in definition of the finite elements composed of a FluidSolidPorousMaterial.
2. During the application of gravity (elastic) load, the fluid phase does not contribute to the material response.
Fluid Solid Porous Material Examples:
|Pressure Dependent Material in saturated, undrained elastic-plastic state (coupled with FluidSolidPorous Material)|
|Example 1||Single quadrilateral element, subjected to sinusoidal base shaking|
|Example 2||Single quadrilateral element, subjected to monotonic pushover|
|Example 3||Single quadrilateral element (inclined by 4 degrees), subjected to msinusoidal base shaking|
|Example 4||Single 3D BbarBrick element, subjected to sinusoidal base shaking|
|Example 5||Single 3D BbarBrick element (inclined by 4 degrees), subjected to sinusoidal base shaking|
|Example 6||A column of quadrilateral element (inclined by 4 degrees), subjected to sinusoidal base shaking|
Code Developed by: UC San Diego (Dr. Zhaohui Yang):
UC San Diego Soil Model:
- NDMaterial Command
- UC San Diego soil models (Linear/Nonlinear, dry/drained/undrained soil response under general 2D/3D static/cyclic loading conditions (please visit UCSD for examples)
- UC San Diego Saturated Undrained soil
- Element Command
- Related References