Advanced Options
Advanced solver settings and convergence controls.
The Advanced panel collects solver behavior, slice-generation, and convergence controls. The defaults are appropriate for most analyses; change them only when you understand the effect. Labels and defaults below match the application.
Strength and tension handling
Zero Shear Strength When Base in Tension
Default on. When a slice base is in effective tension, its available shear strength is set to zero rather than allowed to go negative. A leading toe zone is exempt so that toe-controlled mechanisms are not over-rejected.
Consider Tension for Shear-Normal Calculations
Default on. Controls whether the effective normal term used to pick shear strength may be negative (raw effective term) or is clamped at zero. With it on the raw effective term is used in the shear-normal calculation.
Slice generation
These determine where extra slice boundaries are inserted (see Slice Generation).
Slice at Phreatic Surface Intersection
Default on. Inserts a slice boundary where the slip surface crosses the water table or a piezometric line (water-table pore pressure), or the FEA phreatic surface (FEA groundwater pore pressure). This single toggle covers both piezometric and FEA phreatic crossings.
Slice at Material Boundaries
Default on. Inserts a slice boundary where the slip surface or exposed slope crosses a material boundary, so each slice base stays within one material.
Surface generation
Snap Search Surfaces Within 0.3 m to External Boundary
Default off. When on, trial-surface endpoints lying within 0.3 m of the external boundary are snapped onto it. Off by default so the search uses surfaces as generated.
Convergence and numerical controls
Check m-alpha < 0.2 / Minimum m-alpha
The check is default on with a minimum m-alpha of 0.2. The m_alpha
term enters the slice normal-force solve for Bishop, Janbu, and GLE; when it
becomes too small the normal force is unreliable. With the check on, a surface is
rejected when m_alpha falls below the minimum. The minimum value is editable when
the check is enabled.
Use Steffensen's Method
Default on. Applies Steffensen acceleration to the fixed-point factor-of-safety iteration (Bishop, Janbu, and the GLE fixed-lambda inner loop). It speeds up convergence and does not change the converged result; failed acceleration steps fall back to the ordinary update. It is not the GLE lambda root finder (that is Brent-Dekker by default).
FEA-related options
Keep FEA Stress GLE Interslice Function Non-Negative
Default on. When the GLE interslice function is FEA Stress (FEA-elastic), clips the derived shape so it cannot go negative. See Interslice Functions.
Include Negative FEA Pore Pressure
Default off. Available only with FEA Groundwater pore pressure. When off, negative (suction) FEA pore pressures are clamped to zero; when on, they are kept.
FEA-LEM Check
Default off. This toggle lives in the Analysis Method panel, not the Advanced panel, and appears when a supported method (Bishop, Janbu, Spencer, or GLE) is selected. When on, the app runs an experimental FEA elastic-stress integration along the LEM critical surface and reports that factor of safety alongside the limit-equilibrium result, as a comparison. It does not replace the LEM result.
Experimental
FEA-LEM Check and the FEA Stress interslice function rely on the experimental finite-element solver and are intended for comparison, not as a primary design basis. Both trigger an FEA solve when enabled.
Defaults at a glance
| Option | Default |
|---|---|
| Zero Shear Strength When Base in Tension | On |
| Slice at Phreatic Surface Intersection | On |
| Slice at Material Boundaries | On |
| Consider Tension for Shear-Normal Calculations | On |
| Check m-alpha < 0.2 (minimum m-alpha) | On (0.2) |
| Use Steffensen's Method | On |
| Keep FEA Stress GLE Interslice Function Non-Negative | On |
| FEA-LEM Check | Off |
| Snap Search Surfaces Within 0.3 m to External Boundary | Off |
| Include Negative FEA Pore Pressure | Off |