Rainfall induced slope failures were investigated in a series of centrifuge tests on slopes underlain by different bedrock profiles. These tests were designed to interpret observations made during two full scale landslide triggering experiments, focusing on the effect of hydro-mechanical interactions between a soil layer and bedrock during rainfall events. A climate chamber was designed and constructed for the ETH Zurich geotechnical drum centrifuge (Springman et al. 2001). Two different bedrock profiles were tested. The bedrock was parallel to the slope surface as the benchmark, whereas a convex form was placed at the toe of the slope in the alternative, which has potential to act as a supporting buttress. The changes in the pore pressures at the interface of the soil and bedrock were measured. Moreover, the surface movements were monitored by means of cameras installed in the climate chamber. The hydraulic and mechanical responses of the slopes suggested that a convex form of bedrock at the toe might have a "buttressing" effect to the upper parts of the slope due to arching. Moreover, this stabilising effect would be more pronounced if an efficient drainage system was in place behind the buttress to drain locally high pore pressures.@en