SHANSEP

The SHANSEP model (Stress History and Normalized Soil Engineering Properties) is used for modelling undrained shear strength of certain clay soils (Ladd and Foote, 1974). For a soil subjected to a given stress path, the following equation describes the undrained shear strength.

where:

Stress History Type

The Stress History Type can be based on:

• Overconsolidation Ratio
• Preconsolidation Pressure

Choose the desired option and then select the Define button. This will open the Stress History dialog, in which the following options are available for defining the stress history.

• Constant - a constant value of OCR or Pc is defined for the material
• By depth from upper material boundary - enter values of Depth and OCR or Pc. Depth is measured from the top of the material layer.
• By elevation (y-coordinate) - enter values of Elevation and OCR or Pc. Elevation is the actual y-coordinate.

Material Dependent Vertical Stress

By default, the weight of all materials above a given point, will contribute to the vertical effective stress at that point. If you wish to fully or partially exclude some materials from contributing to the vertical effective stress:

1. Select the Material dependent vertical stress checkbox.
2. Select the Define button.
3. In the dialog, select Add Material to define the material(s) you wish to exclude from contributing to the vertical stress calculation.
4. Define a Vertical Stress Factor for each of these materials (0 to 1).

This is useful for excluding the weight of an added embankment material (for example) from the vertical effective stress calculation, or for simulating the staged addition of layered embankments.