Heavy or prolonged rainfall is the trigger for most slope failures; with one rainfall event sometimes triggering many landslides. Small scale laboratory tests were carried out in order to investigate successive failures occurring in slopes subject to prolonged heavy rainfalls. In this work, a set of experiments was conducted in a small scale flume. A rainfall simulator device was placed on the top of the slope model to provide rainfall at constant intensity. The soil moisture content was monitored by sensors buried inside the slope model. High resolution cameras recorded the occurrence of any movement in the slope. First vertical cracks formed in the upper part of the slope, second the first landslide is observed, third a second landslide is observed. Here, two different cases are considered: in one case debris is manually removed after the occurrence of each landslide to mimic the effect of atmospheric agents and / or fluvial and marine erosion, while in the other one debris is allowed to accumulate at the slope toe. The experimental results help quantifying the correlation between moisture content and landslide onset and highlight how debris propagation and deposition affects the stability of the remaining slope.
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