2A - Slope Stability Analysis Slide2

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Slope Stability Analysis: Slide2
Module 2A
Objectives
1. Features of :
• Modeler (Model building) 
• Engine
• Interpreter (Interpretation of results)
2. Example 1: Setting up a model
3. Specialized Slide2 Features
1. Thrust Line
2. Soil Profile Modeling
3. NEW: Integration with RSLog
1. Example 2: Import from RSLog
4. Multi-Scenario Modeling 
Model
ComputeInterpret
Modeler, Engine, & Interpreter
Modeler: Model Creation
Geometry tools
• External boundary
• Material boundary
• Tension crack
• Water surface
• Weak layer
• Anisotropic surface
• Damage Region
• Soil Profile Boundary
Entity modification
• Move, delete, stretch
Loadings
• Distributed load
• Line load
• Seismic load
Support systems
• Single support
• Pattern support
Modeler: Search Surfaces & Properties
Surfaces
• Circular
• Non-circular
• Slope limits
• Edit
Properties
• Materials
• 20 material strength models
• Supports
• 10 support models
• Tension Crack
Modeler: Project Settings: General
Project settings
• General
• Units
• Failure direction
• Output data
Modeler: Project Settings: Methods
Project settings
• Methods
• 11 stability analysis methods
• Analysis convergence options
Modeler: Project Settings: Groundwater
Project settings
• Groundwater
• 6 Methods
• Finite element analysis
• Excess Pore Pressure
• Rapid Drawdown methods
Modeler: Project Settings: Statistics
Project settings
• Statistics
• Probabilistic analysis
• Spatial variability
• Sensitivity analysis
• Analysis type
• Global minimum
• Overall slope
Modeler: Seepage & Statistics
FE groundwater analysis options 
• Mesh
• Boundary conditions
• Discharge sections
• Hydraulic Material Properties
• 5 conductivity models
Statistical analysis options
• Materials
• Supports
• Loads
• Seismic loads
• Water tables
• Tension cracks
Compute Engine
• Slope stability analysis engine
• Limit equilibrium methods
• Groundwater engine
• Finite element method
Interpreter: Viewing and analyzing results
Filtering options for factor of safety
• Method
• Global
• Surfaces
Queries
• Graph queries
• Information on slices
Support
• View support forces
• View back analysis surface (supports)
Groundwater
• Computed quantities
• Queries
• Flow lines
• Flow vectors
Interpreter: Viewing and analyzing results
Statistical analysis
• Cumulative plots
• Histogram plots
• Sensitivity plots
• Data export
Interpreter: Data Interpretation Tools
Visualization tools that facilitate results interpretation
• Contour and line plots
• Coloring of critical slip surfaces
• Viewing of multiple plots
Interpreter: Reporting Tools
Drawings tools
• Static texts
• Material Properties Table
• Method Results Table
• Drawing tools
• Dimensioning tools
Advanced printing features
• Customized report footer with your 
company logo
• Report Generator
Example 1
Example 1
Basic modelling steps
• Project Settings
• Create slope geometry using import 
DXF
• Create material boundaries using 
import DXF
• Geometry Cleanup
• Import and assign material properties
• Surface Option (Circular surface)
• Compute and Interpret
• Water Surface
• Line of Thrust
• Tension Crack
Thrust Line
Thrust Line
• Represents location of (resultant) interslice forces
• Computed by summing moments of all forces acting on individual slice about 
centre of slice base
• Two schools of thought:
• Solution most reasonable when line of thrust is within sliding mass to prevent 
tension (Sharma et al, XSTABL)
• Nothing wrong with tension (Duncan, Bromhead)
With tension crack Without tension crack
Thrust Line
Eliminating Tension 
Two Methods:
• Tension crack defined in model.
• Adjustment of Mohr failure envelope so that there is no shear strength when 
the normal stress becomes negative.
Tension Crack
• Tension crack terminates the slip surface at the edge of a slice at an 
appropriate depth below the ground surface
• Depth can be estimated using:
𝑑𝑐𝑟𝑎𝑐𝑘 =
2𝑐𝑑
𝛾 tan 45 − 𝜙𝑑/2
Tension Crack
• Should not extend beyond the depth of tension
• If the crack depth is overestimated, compressive forces will be eliminated and 
the factor of safety will be overestimated
• Often, a tension crack has a minor effect on the computed factor of safety
• Introducing a tension crack eliminates numerical instability issues and 
negative stresses
Determining Tension Crack Depth
Perform a series of analyses, varying the depth of the crack
• FS will first decrease as the depth of the crack is increased and tension is 
eliminated, then increases as the depth increases further and compressive 
stresses are eliminated as well
• Cannot be used if the tension crack is filled with water because:
• due to the water pressure, the force on the wall of the tension crack is always 
compressive, and the deeper the crack, the lower the factor of safety.
Slope Stability Analysis – Example II
• Basic modelling steps
• Create slope geometry using
Image Importer
• Import/define material properties
• Define failure surfaces
• Circular surface
• Compute and Interpret
Import Drawing as Image
• Select Pseudo transparent to be able to see the image overlaid on top of geometry and 
select Finish
Assign Material Properties
• Properties > Assign Properties
• Select the material in the Assign Materials 
dialog then select each region to assign the 
property
Soil Profile Modeling
Introduction to Soil Profile
• An extension of the geometry modeling capabilities of Slide2
• Allows you to define a master profile of your material boundaries (e.g. 
geological or soil profile) and ground surface. 
• The profile is used as a base template, over which you can use the regular 
boundary options (e.g. Add External, Add Material) to superimpose different 
slope geometries (e.g. cut back a slope).
• Useful for models with relatively complex material layering, over which you 
would like to define several different slope excavation scenarios
• Helpful to use a Soil Profile with Multi Scenario modeling
Soil Profile and Geometry Workflow Tabs
• Define Profile by activating the 
option in Project Settings
• Import Material and Top Surface 
using DXF imports
• Define and try different slope 
geometries by using Window, 
Polyline and DXF import options 
for adding External Boundary
• Change slope angle or 
• Slope angle wizard
Soil Profile from Borehole Data
• Define boreholes in Borehole Editor
(Profile > Borehole Editor)
• Add borehole(s)
• Specify x- location and top elevation
• Specify material layers and layer 
thicknesses
• Specify borehole interpolation settings
• Create slope geometry by importing 
DXF files
Multi-Scenario Modeling
Multi Scenario Model
• Allows the user to create and 
analyze multiple variations in one 
file
• Users can create an unlimited 
number of variations to analyze
Project Settings Window to select Multiple Scenarios Option
Multi Scenario Analyses allow the user to compare multiple scenarios at once
Groups and Scenarios
• Group – a set of scenarios with the 
same external and material 
boundaries
• Master Scenario – any edits made 
to this scenario affect all scenarios 
in a group
• Scenario – a variation of the master 
scenario with different input 
parameters
Example of the Document Viewer
Adding Scenarios and Groups
• New scenarios and groups can be 
created easily in the Document 
Viewer
• Options to duplicate existing groups 
and scenarios or create new ones
Using the Add Scenario option to create a new 
scenario
Using the Duplicate Group option to create a new group
Using the Duplicate Scenario option to create a new 
scenario
Scenario and Group Management
• Scenario and group properties can 
be altered in the Group and 
Scenario Properties window
• This window allows users to alter 
the name, colour and order of the 
groups and scenarios
Groups and ScenarioProperties window
Viewing Scenarios
• Multiple scenarios can be 
viewed at once using the Tile 
Windows options
• The Synchronize Views 
window allows users to 
synchronize various viewing 
options between scenarios
Editing Scenarios
• Changes to the external boundary 
and material properties in the 
master scenario are applied across 
all of the scenarios in a group
• Edits to features such as water 
table level, loading and supports 
remain unique to each scenario
Multiple scenarios in a single Slide2 file
• Multi-scenario in Project Settings:
• Different Groups
• Different Scenarios
with:
• Different Seismic Loads
• Slope Angle Wizard
Slope Angle of 
41o
Slope Angle of 
34o
End of Module
	Slide 1: Slope Stability Analysis: Slide2
	Slide 2: Objectives
	Slide 3: Modeler, Engine, & Interpreter
	Slide 4: Modeler: Model Creation
	Slide 5: Modeler: Search Surfaces & Properties
	Slide 6: Modeler: Project Settings: General
	Slide 7: Modeler: Project Settings: Methods
	Slide 8: Modeler: Project Settings: Groundwater
	Slide 9: Modeler: Project Settings: Statistics
	Slide 10: Modeler: Seepage & Statistics
	Slide 11: Compute Engine
	Slide 12: Interpreter: Viewing and analyzing results
	Slide 13: Interpreter: Viewing and analyzing results
	Slide 14: Interpreter: Data Interpretation Tools
	Slide 15: Interpreter: Reporting Tools
	Slide 16: Example 1
	Slide 17: Example 1
	Slide 18: Thrust Line
	Slide 19: Thrust Line
	Slide 20: Thrust Line
	Slide 21: Eliminating Tension 
	Slide 22: Tension Crack
	Slide 23: Tension Crack
	Slide 24: Determining Tension Crack Depth
	Slide 25: Slope Stability Analysis – Example II 
	Slide 26: Import Drawing as Image
	Slide 27: Assign Material Properties
	Slide 28: Soil Profile Modeling
	Slide 29: Introduction to Soil Profile
	Slide 30: Soil Profile and Geometry Workflow Tabs
	Slide 31: Soil Profile from Borehole Data
	Slide 32: Multi-Scenario Modeling
	Slide 33: Multi Scenario Model
	Slide 34: Groups and Scenarios
	Slide 35: Adding Scenarios and Groups
	Slide 36: Scenario and Group Management
	Slide 37: Viewing Scenarios
	Slide 38: Editing Scenarios
	Slide 39: Multiple scenarios in a single Slide2 file
	Slide 40: End of Module