Rainfall-induced debris slides represent a significant geological hazard in the Mountainous region. With climate change altering rainfall patterns, extreme rainfall events have shown a rising trend. In the Himalayan region, slope-forming material is not solely composed of rock or soil; instead, it is a combination of both (debris), making it a complex substance. Assessing the engineering behaviour of debris material using traditional soil testing methods is very difficult due to its heterogeneous nature. Reduced-scale laboratory experiments can be used to study the behaviour of debris slides occurring on the hillslopes. In this study, a laboratory-scale flume experiment was conducted to understand the failure process and infiltration triggered by rainfall, utilising materials sampled from a debris slide. The rainfall simulation is carried out using an artificial rainfall simulator, which is designed to generate variable rainfall intensities. High-precision sensors measure key slope parameters such as volumetric moisture content and matric suction or pore-water pressure. Simultaneously, surface displacement of the slope is indirectly monitored, and entire failure process is documented through continuous video recording. Along with the flume experiments, laboratory tests were conducted to determine key properties of the debris material, including grain size distribution curve, in-situ field density, and permeability. It was observed that as rainfall infiltrated, the volumetric water content gradually increased while matric suction decreased, leading to a decrease in effective stress. Based on the experiments and interpretation of the results, a preliminary mechanism possible over debris slides was interpreted.