Parametric Analysis
Vary inputs to study their effect on the factor of safety.
Parametric Analysis sweeps one or more external-boundary vertex positions through a range and re-runs the full slip-surface search at each step, so you can see how the factor of safety responds to a change in geometry.
Scope: single geometric sweep, not probabilistic
Parametric Analysis is a deterministic geometric sweep of boundary vertex coordinates. It is not a probabilistic or Monte-Carlo analysis: there are no input distributions and no probability of failure. JW Slope does not currently offer probabilistic analysis.
How it works
- Assign ranges to vertices. Right-click an external-boundary vertex and choose Apply Parametric Range to set a start and end position (X and Y) for that vertex. You can assign a range to several vertices; each gets its own start and end.
- Set the number of increments. The Increments value (default 5) controls how many steps the sweep is divided into.
- Run. For each increment the boundary geometry is interpolated and the full search runs, producing one result per increment.
The geometry at each increment is a linear interpolation between the start and
end of every ranged vertex. With N increments the sweep evaluates steps from 0
to N: at fraction t = increment / N, each ranged vertex moves to
position = start + (end - start) * tSo increment 0 is the start geometry, increment N is the end geometry, and the
intermediate increments are evenly spaced between them. Vertices without a range
stay fixed.
Results
Each increment produces one factor of safety per enabled analysis method. Results are plotted as FOS versus increment, with one line per method, and the lowest factor of safety across the sweep is reported along with the increment at which it occurred.
Apply Increment
After a sweep, the Apply Increment control lets you select an increment and commit its interpolated geometry back to the model — for example, to keep the geometry that produced the lowest factor of safety. By default the selection follows the increment with the lowest factor of safety.
Practical notes
- Parametric Analysis varies boundary vertex coordinates only. It does not sweep material strength, water levels, loads, or search settings.
- Because every increment runs a complete search, total run time scales with the number of increments. Start with a small number of increments and refine.
- At least one vertex must have a range assigned, the boundary must have at least three points, and Parametric Analysis must be enabled before a run can start.