INVESTIGATION OF RAINFALL INDUCED LANDSLIDES NEAR MOHAND ALONG NH 307

Abstract

Landslides occur frequently along the NH 307 during the monsoonal season. The NH 307 is of strategic importance as it is the sole path connecting the cities of New Delhi and Dehradun. It has been observed that remedial measures are taken by the respective authorities to repair the failed slope, however the retaining structures collapse every year creating a traffic disruption.The NH 307 mainly contains soil slopes comprising of conglomerate, mudstone and sandstone. Upon identification of the landslides a preliminary field investigation is carried out to collect the sample for various Geotechnical laboratory tests and document the geometrical characteristics of the landslide. Next the work flow is divided into two stages, namely the Dry Analysis and Wet Analysis.In the Dry Analysis, several laboratory tests are conducted such as the Sieve Analysis, X Ray Powder Diffraction and Direct Shear Test, to infer the strength properties of the sample. Leveraging the internal properties and geometrical characteristics, a numerical simulation of the landslide is conducted using the Finite Element Method in software Phase 2. In the next stage the laboratory experiments and simulation are repeated, for a saturated sample. However for a more accurate representation of the slope’s extent a Digital Elevation Model (DEM) is used, from Alaska Satellite Facility (ALOS PALSAR) using ARCGIS. Lastly to map the Landslide Susceptibility in the region, 17 basins around the site of study are chosen. Based on numerous areal and linear parameters of the basin a Landslide Hazard Zonation Map is generated, to cover all possible sites of failure along the NH 307. Finally remedial measures for the Landslides identified are suggested with a Zonation Map to further identify areas with hazardous slopes