## Infinite Slope v. 2.01.

Software features and limitations.

Scheme of the slope as designed in the graphical interface.

**Features**

The position of free phreatic surface has a determinant role on stability conditions, therefore it is very important to be able to control its depth

*z*

*w*.

The polygon of forces for the slice is useful to control how the equilibrium evolves when changing a parameter.

While user can evaluate the factor of safety

*F(z)*for a generic slip surface (at depth

*z*) often its necessary to compare the obtained value to the minimum value of

*F*(at depth

*z*

*crit*) called the

*Factor of safety*of the slope.

All main variables can be controlled in interactive mode in order to understand their influence with an immediate visual perception.

The presence of the bedrock at depth

*z*

*bed*helps to give a lower limit to depths for the position of the failure surface, which makes the research of a critical depth

*zcrit*more realistic. The complete project passes through three main moments: Input of data -> Analysis of stability -> Design of intervention.

All features included in version v.2.01 are listed below:

- Input of weights either via porosity
*n*and unit weight of solids*γs*or directly through*γsat*,*γ*and*γd*. - Variable position of free phreatic surface at depth
*zw*. - Unit weight of the soil are considered separately above and below the groundwater surface.
- Unit weight above groundwater surface can be given different to the dry unit weight.
- Factor of Safety
*F(z)*for a generic slip surface (at depth*z*). - Factor of Safety
*F*of the slope, wich represent the minimum value corresponding to the critical slip surface (at depth*zcrit*). - Back analysis of a failure condition to determine
*φ'*or*c'*. - Position of the bedrock at depth
*zbed*which represent a layer of infinite strength. - Updated scheme of slope geometry with clear indications.
- Polygon of forces for the equilibrium of the slice.
- Suggestions and warnings about input data and on the results.
- Optional title to the project.
- Assessment of slope stability.
- Variable allowable value of the Factor of Safety.
- Unit weight of the soil above groundwater free surface can be input separately.
- Forces, stresses and pore pressures calculated for the single slice of unitary width.
- Mohr-Coulomb's elastic-perfectly-plastic constitutive law.
- Both static condition and seismic (pseudo-static) force can be considered through the horizontal and the vertical component.
- The minimum allowabe factor of safety can be set.
- It is possible to run the analysis with a known failure surface; to set the program to search the critical depth zcrit at which F is minimum or to perform back analyses.
- Back analyses can be performed either to determine fi' or c'.
- The visual approach helps to: better understand the influence of the parameters; explore more solutions and interpretate the results.
- The presence of the bedrock, at a depth zbed, helps to give a lower limit for the development of a failure surface, which makes more realistic the research of a critical depth zcrit (at which the factor of safety F is minimum).
- It is possible to input a project title.
- It is possible to save and open an analysis projects.
- All forces and stresses concerning the elementary slice are reported.
- It is possible to design interventions as the use of drainage trenches or bored pile walls.
- A polygon of forces is continuously shown for the equilibrium of the elementary slice.
- A sketch of the actual longitudinal section of the slope and the sketch of the longitudinal section of the slope as designed are shown and continuously updated.
- Stability assessment is constantly updated.
- Remarks and suggestions are constantly shown.
- An analysis report can be printed.

**Limits of application**

At the moment this version has the following limitations:

- The model is suitable to analyse stability conditions of slopes with direction of stratification parallel to the slope. In many cases of mudflows and in any case where the failure surface is expected or found planar and parallel to the slope. For slopes made of fine grained soils in deep homogeneous layers the used model is often not suitable to represent a correct interpretation of failure mechanisms (circular or not planar) and isn't able to give a reasonable factor of safety for the slope.
- Groundwater flow must be parallel to the ground surface or absent.
- Seismic forces are pseudostatic and no dynamic effects is taken into account.
- Unsaturated soil theory is not applied.
- Only drained failure conditions are considered.