I.L.A. is a complete slope stability analysis program that also incorporates powerful features for retaining system designing.

The slope analysis and design can be performed using the Sarma method, whose numerical stability increases the reliability of the calculations.

The classic Bishop, Jambu, Morgenstern & Price and Bell methods are also available; this allows to compare the results and obtain a more complete and affordable elaboration.

The failure surfaces can either be defined as circular or planar surface families or even individually, as polygonal surfaces, and therefore have any shape whatsoever.

The analysis can be carried out under drained or undrained conditions, also considering water pressures, surcharges, and seismicity (pseudostatic analysis).

The calculation method used for designing the retaining system is of particular importance.
Common programs only allow the determination of the safety factor that can be obtained when a given force is applied to the slope. The program uses instead complex inverse formulae which, given the geotechnical parameters and a required safety factor, restitute the reaction force that the retaining system should offer to obtain such a safety factor.

The program automatically extends the retaining system analysis to all the failure surfaces, offering a complete and immediate result without manual iterations of the calculation.

In the case in which the reaction forces result to be higher than the allowable loads, the safety factor that corresponds to the actually obtainable reaction force is calculated.

The program also yields excellent results for the calculation of reinforced slope.

EXAMPLES OF GRAPHIC OUTPUTS

Here are some examples of program-generated graphic outputs:

• Stability analysis with overloads and circular failure surfaces passing through the foot of the slope;
• Stability analysis with overloads and circular failure surfaces passing above the top of the slope;
• Example of stratified soil with a discontinuity dipping inward the slope;
• Example of stratified soil with a discontinuity dipping outward the slope - a water table is present;
• Example of stratified soil with a lens;
• Stability analysis with planar failure surfaces passing through a point;
• Stability analysis with circular failure surfaces tangent to a straight line;
• Stability analysis with circular failure surfaces passing through two points;
• Complete example of the output window for the calculation of the retaining system.