Laboratory rainfall-induced slope failure in a soil from the Colombian coffee region

There are few studies on the processes involved in landslides in the soils of the Colombian coffee region in relation to the soil water content. In order to contribute to this knowledge, several experiments over a terrain model under simulated rainfall were conducted. Seven experiments on laboratory slope models, 1.8 m(2) base, 1.0 m height, and 32 degrees slope, with soil bulk density and soil horizons arrangement similar to in situ conditions, were built. Samples of altered residual soil derived from granitic rocks were collected in the municipality of Ibague - Colombia from the surface down to 1.6 m depth. In each laboratory model, eight suction tensiometers (0 to - 85 kPa) were located, and measurement under simulated rainfall was done. The results indicated a relationship of mass movements with hydrological processes occurring in the slope, related to soil permeability, rainfall intensity and duration, and water table changes. The major portion of soil slope instability cases was related to a saturated condition of the slope toe.