How to verify the slope stability for a critical circular and a polygonal slip surface (using optimization) 
The aim is to perform a slope stability analysis for a slope with a gravity retaining wall and surcharge under drained conditions. This is a permanent design situation and the required factor of safety is FS = 1.5.  
In GEO5, each program has the same top-down workflow interface that makes the software extremely easy to learn and use. This workflow offers a more efficient process for performing the analysis. 
 
The slope stability problem is solved in a two-dimensional environment, but can also be visualized in 3D by simply clicking the "3D" button. Two types of approaches to stability analysis are implemented in the program - classical analysis according to the factor of safety and the analysis following the theory of limit states. We will solve the problem using the factor of safety analysis, modelling a circular slip surface using the Bishop method and a polygonal one using Spencer. The slip surface can also be modelled using Fellenius/Petterson, Spencer, Janbu, Morgenstern-Price, Shahunyants, and ITF method or as a polygonal one using the Sarma, Janbu or Morgenstern-Price, Shahunyants and ITF method. 
 
 
 
Below, you can see how to use GEO5 to find the critical slip surface according to the factor of safety in just 10 fast and easy steps (with GIFs). 
 
 
STEP 1 
Open the GEO5 Slope Stability program. 
 
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STEP 2 
In the Settings frame click on “Select settings” and choose option No. 1 – “Standard – safety factors”. 
 
 
STEP 3 
In the Interface frame, click on “Setup ranges” and input the coordinate range of the assignment. 
 
 
STEP 4 
Click on “Add interface” to model the terrain by adding the interface coordinates. 
 
 
STEP 5 
Add the soils' properties and their parameters in the Soils frame using the “Add” button.  
 
 
STEP 6 
In the Rigid body frame, model the gravity retaining wall as a rigid body and input the unit weight. 
 
 
STEP 7 
Assign areas with the soils created in the Assign frame. 
 
 
STEP 8 
Define a strip surcharge in the Surcharge frame. 
 
 
STEP 9 
Open the Analysis frame, where you can enter the initial slip surface using the coordinates 
of the centre (x, y) and its radius or using the mouse – by clicking on the interface to enter three points through which the slip surface passes. Set the type of analysis to “Optimization” and then perform the verification by clicking on “Analyze”. 
 
 
STEP 10 
Add another analysis using the "+" button and convert the original circular slip surface to a polygonal slip surface using the “Convert to polygon” button. Perform a verification again by clicking on "Analyze" and finally compare the results. 
 
 
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Tagged as: Tutorials
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