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Soil and Water Engineering  >  Modeling Software  >  Slope Stability Software  >  XSTABL

XSTABL v5 -- An Integrated Slope Stability Analysis Program for Personal Computers

Description of XSTABL

XSTABL provides an integrated environment for performing slope stability analyses on an IBM personal computer, or compatible, running MS-DOS. The program provides an intuitive user friendly interface and the analytical philosophy behind the popular slope stability program STABL, which was developed at Purdue University.


The Generalized Limit Equilibrium (GLE) method has been implemented in XSTABL. This method allows factors of safety to be calculated for force and moment equilibrium or for force equilibrium only, using different interslice force angle distributions. With this approach, the user can readily calculate the factor of safety according to Spencer's, Morgenstern-Price, or one of the methods proposed by the Corps of Engineers.

If an analysis requires a search for the most critical failure surface, the simplified Bishop and Janbu methods of analysis are selected due to their relative ease of use. The program may be used to either search for the most critical circular, noncircular, or block-shaped surface, or alternatively, to analyze a single circular or non-circular surface. The critical surface is identified by automatically generating and analyzing failure surfaces between defined initiation/termination ranges or by connecting points randomly located within search boxes specified by the user. This aproach minimizes the required input parameters and can be effectively used to confine the surface generation within a narrow, well-defined zone. The soil strength along the failure surface may be described as either conventional (i.e., C, ø), undrained or non-linear Mohr Coulomb and can be either isotropic or anisotropic. The undrained strengths are assigned as a function of the vertical effective stress.

For effective stress analysis, pore water pressure may be simulated by specifying:

  1. A piezometric surface;
  2. Multiple phreatic surfaces;
  3. Pore water pressure grid;
  4. Constant pore pressure;
  5. Pore pressure parameter ru.

[Adapted from XSTABL v5 brochure, 6/1/94]


The USFS has a site license for use of the XSTABL software. We may use it for official USFS work only. Contractors may use a Forest Service copy of XSTABL for work on official FS projects, but must surrender to the Forest Service all copies of the software at the completion of the project.

If you are using XSTABL and have not notified our office, please let us know, so we can more easily keep Forest Service XSTABL users aware of new versions.

To get a copy of XSTABL:

FS users:
Contact the Regional Engineer at the Regional Office. He or she will have been supplied a copy of XSTABL and several manuals for distribution within the region. Those in Forest Service Research should contact a nearby Regional Office for a copy.

Then, please notify David Hall that you have a copy, so that we can let you know of updates to XSTABL, or other important issues, and read our hints on using XSTABL under current Forest Service machines.

If XSTABL is not available to you through these channels, you can download the software over the Forest Service Intranet. This site is accessible only to Forest Service computers.

We can not supply XSTABL for non-Forest Service use. It is available commercially from the developer:

Dr. Sunil Sharma
Interactive Software Designs, Inc. (

For more information on XSTABL, select one of the following: