Retaining wall design, checked the classical way.

From soil parameters and wall geometry, Volex computes active and passive pressures, the sliding and overturning factors of safety, bearing pressure under the toe, and the stem and base reinforcement.

The earth pressure coefficients are validated against Craig's 'Soil Mechanics' tables — the same numbers you would look up by hand — so there is no argument about where Ka came from. Gabion and sheet-pile walls are separate modules.