6.2 Inspect Analysis Results
- Once the analysis is complete, the results can be inspected using the Inspector Tool under the Analysis tab of the tool palette, or by selecting Inspector Tool from the Analysis menu.
Analysis Results Summary
- The Analysis Results view will be presented automatically upon completion of the analysis.
- A summary view with the method, search type, number of slip centers attempted, number of trial surfaces attempted, removed, and non-converged will be displayed along with other analysis parameters.
- The minimum factor of safety identified by the analysis will be highlighted and displayed in the summary view.
- Click the button next to Trials Removed to see the detailed stats of any removed trials.
- Select the Selected Slip Center tab in the Analysis Results view to view details for the currently selected slip center.
- Using the Inspector Tool , click over any slip center displayed by a search grid or specified surface to select the slip center and view it's details. The trial slip surface with the minimum factor of safety for the selected slip center will be displayed on the drawing.
- Click the button next to Trial Warnings to see any warnings generated for the minimum FOS trial at the selected slip center.
Viewing Slice Details
- Using the Inspector Tool , click over any slice displayed on the drawing to present the Slice Inspector.
- The Slice Info tab displays a free body diagram showing all the forces acting on that slice. Click the details button and scroll through the table to view slice dimensions.
- The Force Polygon tab displays a force polygon of the forces acting on that slice. A green circle indicates good force closure, while a red circle indicates the slice is not in force equilibrium. Click the details button and scroll through the table to view the slice forces.
Viewing Custom Force/Stress Plots
- Click the Plots button to create a custom plot of selected Forces or Stresses over the slip surface segment.
- Click the disclosure triangle on the right side of the plot to select which forces / stresses to display.
- Click the disclosure triangle above the plot to select whether to display the forces by distance or slice number.
- Click the Align Drawing to align the drawing geometry with the current location of the custom plot.
- The following forces can be plotted over the slip segment:
- Slice Weight - The force 'W' acting vertically downwards at the slice centroid. It is the sum of the weight of each region within the slice.
- Base Normal - The force 'P' acting normal to the base of the slice. See the Methods section to see how it is calculated.
- Base Pore Force - The force 'U' acting normal to the base of the slice. It is equal to the base pore pressure summed over the base length of the slice.
- Mobilized Base Shear - The shear force 'Sm' acting parallel to the slice base, calculated from the Mohr-Coulomb failure criterion.
- Interslice Normal - The interslice force 'E' acting normal to the side of the slice, calculated by summing forces in the horizontal direction.
- Interslice Shear - The interslice shear force 'X' acting parallel to the side of the slice, calculated as (X / E = tanθ) using Spencer's method or (X = E * f(x) * λ) using the GLE method.
- Seismic - The seismic force 'kW' acting perpendicular to the weight force, acting in the direction of slip.
- Reinforcement - The summation of any reinforcement forces acting on the slice.
- External - The summation of any external forces acting on the slice.
- Note that all forces reported are kN (per meter cross-section) or lbf (per foot cross-section).
- The following stresses can be plotted over the slip segment:
- Overburden - The stress acting vertically downwards due to the weight of the slice, and any top external hydrostatic loads applied.
- Base Normal - The stress acting normal to the base of the slice.
- Base Pore Pressure - The pore pressure acting normal to the base of the slice.
- Mobilized Base Shear - The mobilized shear stress acting parallel to the slice base.
- Interslice Normal - The normal stress acting on the interslice boundary.
- Interslice Shear - The shear stress acting on the interslice boundary.
- Available Base Cohesion - The cohesive component of the shear stress available to be mobilized along the slice base.
- Available Base Friction - The frictional component of the shear stress available to be mobilized along the slice base.
- Available Interslice Shear - The sum of the cohesive and frictional components available along the interslice boundary, summed from all materials encountered along the slice boundary.
- Note that all stresses reported are kPa or psf.
Viewing Line of Thrust (Spencer/GLE Methods Only)
- If you have completed an analysis using the Spencer or GLE method, interslice shear forces are included in the analysis, and a line of thrust for the interslice forces may be calculated to satisfy moment equilibrium for all slice forces about the centre of the slice base.
- Click Show Line of Thrust in the analysis results pane to show the line of thrust for the currently selected trial.
- It is calculated starting from both the left and right boundaries of the trial slip, knowing the thrust position at the boundary slices (including any external boundary forces), and proceeding slice-by-slice towards the middle slice.
- If the line of thrust passes outside the soil mass, it is likely that one of the physical admissibility criterion (Base Tension, Interslice Tension, Interslice Shear > Available Shear) has been violated. Although a factor of safety has been calculated that satisfies overall force and moment equilibrium, the resulting internal forces can not be realistic, and the solution should be treated with caution.
Viewing FOS-Convergence Diagram (Bishop/Janbu Methods Only)
- If you have completed an analysis using the Bishop's Simplified or Janbu's Simplified method, a FOS-Convergence Diagram is available to be plotted.
- Click FOS-Convergence Diagram from the Plots button and you will be presented with a diagram showing the convergence history for the force or moment factor of safety.
Viewing Moment-Force Factor of Safety Diagram (GLE Method Only)
- If you have completed an analysis using the GLE method, a Moment-Force FOS Diagram is available to be plotted.
- Click Moment-Force FOS Diagram from the Plots button and you will be presented with a diagram showing the variation of the moment and force factors of safety with the specified range of λ.