Debris flow in c-ϕ soil: experimental analyses of pore pressure variations, crack percentage, digital image correlation (DIC) and particle image velocimetry (PIV).

Debris flow is the aftermath of soil losing its strength due to an increase in moisture content, which is initiated by Rainfall. This study investigates rainfall-induced debris flow in c-ϕ soil predominantly found in the Western Ghats, India. The experimental setup utilised the tilting flume technique to simulate a 45-degree slope, replicating field conditions in terms of field density and natural moisture content. Excess pore water pressure (EPWP) variations were monitored during simulated rainfall events with an intensity of 30 mm/h. The findings indicate that the decrease in EPWP observed during the experiments Following a peak value and coincides with the initiation of soil movement, which occurs after the formation of shear cracks on the soil surface. To substantiate these observations, a masking algorithm based on OpenCV was employed to analyse fluctuations in crack percentage. Particle image velocimetry (PIV) and Digital Image Correlation (DIC) quantified particle velocity-displacement dynamics using high-definition camera imagery over time, which validated the initiation of landslides. It was observed that the rapid decline in EPWP serves as a critical precursor to potential landslide occurrences, underscoring the pivotal role of these metrics in early landslide prediction and risk assessment. This research contributes valuable insights into understanding landslide mechanics under controlled laboratory conditions, with implications for early landslide detection and hazard mitigation strategies in landslide-prone regions. [ABSTRACT FROM AUTHOR]