Slice Generation
How the failure mass is discretized into slices.
Before any method runs, JSlope divides the sliding mass above a trial slip surface into vertical slices. Every LEM method starts from the same slices, so the slicing rules below apply regardless of which method you select.
Target number of slices
The Target Number of Slices (default 30, minimum 8) sets how many slices the slicer aims to create. It is a target rather than an exact count: the slicer first places any required slice boundaries (see below), then distributes the remaining slices to keep slice widths roughly even, so the final count can differ slightly from the target.
A higher count gives smoother per-slice results and slightly more accurate factors of safety at the cost of speed. The default of 30 is adequate for most slopes.
Automatic (required) slice boundaries
Beyond the two surface endpoints, the slicer inserts a slice boundary wherever the slip surface crosses a feature that the strength or pore-pressure calculation needs to resolve cleanly. These insertions are controlled by advanced options (all default on; see Advanced Options):
| Feature | Advanced option | Default |
|---|---|---|
| Material boundary crossings (slip surface or exposed slope) | Slice at Material Boundaries | On |
| Phreatic surface / piezometric line crossings (water-table pore pressure) | Slice at Phreatic Surface Intersection | On |
| FEA phreatic surface crossings (FEA groundwater pore pressure) | Slice at Phreatic Surface Intersection | On |
Generated surfaces may also carry their own preferred boundary positions, which are honored as required boundaries.
Why required boundaries matter
Without a boundary at a material or water crossing, a single slice would straddle two different materials or two different pore-pressure regimes, smearing the strength and pore force over its base. Required boundaries keep each slice base within one consistent region.
Distributing slices
The required boundaries fix the segments that must exist. The slicer then distributes the target number of slices across those segments in proportion to their width, so each region is sliced about as finely as the overall target implies, and slice widths stay roughly uniform.
Tension-crack clipping
If a tension crack applies, the trial surface is clipped at the tension crack before slicing, so the sliced mass does not extend past the crack. Tension-crack forces (for example water pressure in the crack) are then applied to the affected slice.
More required boundaries than the target
The required boundaries are always kept. If they alone divide the surface into more intervals than the Target Number of Slices, each interval becomes one slice, so the surface is analyzed with more slices than the target rather than being rejected. Slide2 treats its required slice boundaries the same way.
Many closely spaced crossings
A geometry with many closely spaced material or water crossings then has one slice between each pair of crossings. Raise the Target Number of Slices to place additional slices between them as well.
Other slicing behavior
- The toe slice is forced triangular so the exposed toe does not produce a sliver with a false vertical edge.
- Each slice stores its geometry, area and centroid, base length and inclination, sampled material strength, pore force, and accumulated loads and seismic forces, which the analysis methods then consume.