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<p>Rainfall-induced landslides are quite common in hilly regions during the monsoon season. This study investigates the failure mechanism of a catastrophic landslide that occurred in Tiruvannamalai District, Tamil Nadu, India, on December 1, 2024. Field investigations, geotechnical analysis, weathering characterization, numerical modeling, and remote sensing analysis are carried out. The landslide was triggered by rainfall due to Cyclone Fengal. It destroyed five houses and buried seven people in the run-out path. The landslide area was analyzed using Sentinel-1 Synthetic Aperture Radar (SAR) data, Sentinel-2 optical imagery, and the digital elevation model (DEM). The pre- and post-event satellite images reveal significant surface deformation, with a decrease in SAR backscattering, indicating terrain disturbance. Slope and elevation data indicate that surface deformation patterns are present at elevations ranging from 180 to 260&#xa0;m. The landslide was classified as a complex rock slide-debris avalanche. The Schmidt rebound hammer test measured the hardness of Charnockite rock, revealing lower values in weathered areas. The soil at the site was classified as clayey sand, with medium permeability. Iron and aluminum oxides create aluminum silicates that enhance soil stability in dry conditions. However, during rainy seasons, infiltration of rainfall disrupts the cohesion, weakening shear strength and increasing failure risk. The seepage analysis simulated 48&#xa0;h of rainfall at 4.9&#xa0;mm/h, indicating a shift toward a saturated state. The pore water pressure was increased from − 48 to 52&#xa0;kPa, and the degree of saturation rose from 0.50 to 0.98. This led to a reduction in matric suction and effective stress, resulting in the landslide.</p>

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Failure mechanism of the rainfall-induced landslide in December 2024 in Tiruvannamalai, India: insights from the field, geotechnical, and remote sensing observations

  • 期刊论文

  • 发表日期：

    2025年7月21日

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  • Sembulichampalayam Sennimalai Chandrasekaran,
  • Ramesh Kesavaram,
  • Surendar Manickam,
  • Ganapathy Pattukandan Ganapathy,
  • Arunava Ray,
  • Pitchaikani Nivethiha,
  • Abishek Thamizhmaran

摘要

Rainfall-induced landslides are quite common in hilly regions during the monsoon season. This study investigates the failure mechanism of a catastrophic landslide that occurred in Tiruvannamalai District, Tamil Nadu, India, on December 1, 2024. Field investigations, geotechnical analysis, weathering characterization, numerical modeling, and remote sensing analysis are carried out. The landslide was triggered by rainfall due to Cyclone Fengal. It destroyed five houses and buried seven people in the run-out path. The landslide area was analyzed using Sentinel-1 Synthetic Aperture Radar (SAR) data, Sentinel-2 optical imagery, and the digital elevation model (DEM). The pre- and post-event satellite images reveal significant surface deformation, with a decrease in SAR backscattering, indicating terrain disturbance. Slope and elevation data indicate that surface deformation patterns are present at elevations ranging from 180 to 260 m. The landslide was classified as a complex rock slide-debris avalanche. The Schmidt rebound hammer test measured the hardness of Charnockite rock, revealing lower values in weathered areas. The soil at the site was classified as clayey sand, with medium permeability. Iron and aluminum oxides create aluminum silicates that enhance soil stability in dry conditions. However, during rainy seasons, infiltration of rainfall disrupts the cohesion, weakening shear strength and increasing failure risk. The seepage analysis simulated 48 h of rainfall at 4.9 mm/h, indicating a shift toward a saturated state. The pore water pressure was increased from − 48 to 52 kPa, and the degree of saturation rose from 0.50 to 0.98. This led to a reduction in matric suction and effective stress, resulting in the landslide.