Limit Equilibrium Method (LEM)

Create Control Data for Slope Stability Analysis.  

Applicable Modules:

From the Main Menu, select Analysis | Design > Design and Report > Analysis Case > Slope Stability (LEM) Analysis > Analysis Control Data

Limit Equilibrium Method (LEM)

Limit Equilibrium Method is used to carry out Slope Stability Analysis.

Analysis Method

Bishop

Fellenius

Janbu

Spencer

Morgenstern - Price

Sarma (Vertical)

Using Function

In case of Morgenstern - Price method, it is to calculate the vertical force of slice using function

Half Sine is default one. Refer to LEM User Defined Function.

  < Limit Equilibrium Method (LEM) >

α / β

In case of Sarma method, the relation between horizontal and vertical force of slice is defined by Mohr-Coulomb failure criteria.

X = λ x ( αh + Etanβ )

α : cohesion

β : friction angle

h : slice height

No. of Iterations and Errors

Maximum number of iterations

Maximum number of iterative calculations.

No. of Slices

Number of slices to be assumed at the failure surface.

Safety Calculation Tolerance

Convergence criterion for safety factor.

Minimum Thickness of Slice

Minimum thickness of failure surface.

Slope Direction

Select the direction of Analysis model.

Left to Right Direction

Sloping down from left to right.

Right to Left Direction

Sloping down from right to left.

Advanced Option for LEM





Advanced option to define the calculation method of slice force

Slice Segmentation
Equal Length / Equal Width

Reinforcing Effect

Consider Reinforcement Force
Check : Including reinforcing force in the equilibrium equation.
Uncheck : Excluding reinforcing force from the equilibrium equation.

Reinforcement Load
Specify the unit of reinforcement load (Stress / Force)

Print Result File

Calculation results for all of assumed failure surfaces.

Initial Water Level

Enter the underground water level condition. A function created by a basic function or the Water Level Function can be specified.

Use of Optimization

If checking the button 'Use of Optimization', the below options about optimization method is activated and optimization analysis to find critical slip surface is conducted.

Convergence Tolerance

Specify optimization convergence tolerance. When analyzing in order to find critical slip surface, optimization is quitted if difference between factor of safety of slip surface divided before and factor of safety of slip surface divided currently is less than or equal to convergence tolerance.

Number of Points on Slip Surface

Specify initial value and maximum of points on slip surface. Optimization is conducted increasing the number of slip surface from initial value to maximum value.

< Define Optimization analysis >

Variation range of Coordinate of Point

Specify variation range of coordinate of point on slip surface.

Result Output

Specify method of result output. If selecting 'Last step', result of last step which is the lowest factor of safety is output, and if selecting 'All step', results from each slip surface are output.

Sensitivity : Check sensitivity analysis. But, It can not be considered with optimization analysis at the same time.

Probability : Check probability analysis. But, It can not be considered with optimization analysis at the same time.

- Sampling Method : Latin-Hypercube method. (Refer to analysis manual)

- Number of Samples : Enter the number of samples.

User Spatial Variation : Define spatial variation directly.

- Sample Each Slice : Calculate parameters of each material defined about probability analysis applying each slice  of fracture surface differently.

- Use Sampling Distance : Calculate parameters of each material defined about probability analysis applying on the standard of distance coordinates each slice base of fracture surface differently. Enter sampling distance and apply based on the most left coordinates from total slope surface.

Click , after applying the selected Analysis case, the dialog box will close upon clicking.

Click or press the ESC key to close the dialog box.