Liner Type: Geosynthetic
To define the support properties of reinforcement materials such as geogrids or geotextiles:
- Select Define Liners
from the toolbar or the Properties menu. - Select Liner Type = Geosynthetic.
- Enter the properties described below. Properties are specified per unit width of material.
NOTE: for an overview of modeling Geosynthetics in RS2, see the Define Geosynthetics topic. This discusses the different ways of modeling Geosynthetic support, including the properties of the Geosynthetic/soil interface.
Initial Conditions
For a Geosynthetic liner, the initial conditions include the Unit Weight and Initial Temperature.
Unit Weight
For Geosynthetic and Cable Truss liner types, the Unit Weight option is only available when Thermal Analysis method is set to Steady Thermal FEA or Transient Thermal FEA in the Project Settings menu, AND the Activate Thermal checkbox is selected in this dialog.
Note that for Geosynthetic and Cable Truss liner types, the unit weight will only be utilized for the thermal analysis.
Initial Temperature
The Initial Temperature option is only available when Thermal Analysis is enabled in the Project Settings menu AND the Activate Thermal checkbox is selected in this dialog.
Tensile Modulus
The Tensile Modulus represents the elastic response of the Geosynthetic to a tensile load. It is equal to the slope of a force versus strain graph, per unit width of material. Strain is the elongation strain measured in the direction of the applied tensile force.
Strength Properties
The following Strength Properties are applicable for a Geosynthetic.
Material Type: Elastic
If the Material Type = Elastic, then the strength of the Geosynthetic is not considered (i.e. there will be no upper limit to the tensile load which can be sustained by the Geosynthetic). The only property of the Geosynthetic which will be used in the analysis is the Tensile Modulus.
Material Type: Plastic
If the Material Type = Plastic, then you may enter values of Tensile Strength (peak) and Tensile Strength (residual).
- Peak Tensile Strength - determines the maximum load (force) which can be sustained by the Geosynthetic, per unit width of material.
- Residual Tensile Strength - if the peak Tensile Strength is reached, then the Geosynthetic will fail in tension, and the strength (force in the Geosynthetic) will revert to the residual Tensile Strength. If the Geosynthetic has no residual tensile strength then enter zero for this parameter.
Axial Strain
This option allows users to assign axial strain to simulate liner contraction/expansion. In terms of the sign convention, negative input parameter (-) indicates contraction, and positive (+) represents expansion. The liner axial strain can be staged, using the Stage Geosynthetic Properties option in the dialog.
Thermal
This section is only available if the Thermal Analysis is enabled in the Project Settings menu.
You can select the checkbox for Activate Thermal to include thermal properties for liners. Available parameters depend on the involved thermal method, as described below.
Thermal Method: Static Temperature
If thermal method = Static Temperature, available properties include the Static Temperature, Thermal Expansion, and Initial Temperature (under Initial Conditions section).
The Static Temperature parameter can be defined either as a Constant value or a Grid (temperature girds can be entered in Temperature Grid from the Thermal menu).
Thermal Method: Steady Thermal FEA
If thermal method = Steady Thermal FEA, available properties include the Thermal Conductivity, Thermal Expansion, Initial Temperature, and Unit Weight (under Initial Conditions section).
Thermal Method: Transient Thermal FEA
If thermal method = Transient Thermal FEA, available properties include the Thermal Conductivity, Specific Heat Capacity, Thermal Expansion, Initial Temperature, and Unit Weight (under Initial Conditions section).
Stage Geosynthetic Properties
The properties of a Geosynthetic can be modified at different stages of a multi-stage model, with the Stage Geosynthetic Properties option. This could be used, for example, to simulate a decrease in Geosynthetic strength or stiffness over time.
The Geosynthetic properties can be increased or decreased by user-defined factors at different stages. See the Stage Liner Properties topic for details about staging Geosynthetic properties.
Flexural Properties of a Geosynthetic
By definition in RS2, a Geosynthetic has zero flexural rigidity. If you need to model a Geosynthetic with flexural rigidity (e.g. a stiff geogrid), then you should model this as a regular liner (e.g. Liner Type = Standard Beam), and enter appropriate properties to simulate the flexural behaviour.