Highway Research Record

III. GEOTECHNICAL ENGINEERING
ON GOING PROJECTS
Investigation, Instrumentation and Monitoring of Patalganga Landslide on NH-58, Uttaranchal

Date of Start: March 2002
Central Road Research Institute, New Delhi (R, I)

Present Status and Progress
Topographic (contour) Map on 1:500 scale of the Patalganga Landslide and 1:1250 of the Patalganga watershed have been prepared based on field, GIS and Remote Sensing Technique. Geological, geomorphological, tectonic & drainage maps of Patalganga landslide as well as the watershed were also prepared based on field satellite data. Soil samples of Patalganga Landslide were tested for its Geotechnical properties. The wooden peg markers installed earlier were now replaced with the steel marker constructed on a concrete base. 25 Nos. of steel markers are installed on the slope to monitor the surface movements.
The final progress of the project was presented before a PMC of DST held at COER at Roorkee on 22 February 2005. Report completed and shall be submitted to DST in the month of July 2005.

Findings / Conclusions
Relationship between the various parameters pertaining to geological, geomorphological, geostructural, geotechnical and anthopogenic factors and the occurrence of landslides in the Patalganga valley was developed using GIS technique. The relationship will help to understand the mechanism of landslide development in the valley and therefore can be used for developing future strategies for positive development in the valley. Patalganga landslide was understood to be deep-seated but the crustal movement monitoring indicated surfical movements and, therefore, the measures to arrest the movements shall be suggested accordingly.

Limitations
The study so far done indicate Patalganga Landslide having surface movement only. Deep seated movement at this stage is ruled out and the slope is therefore proposed to be monitored only for its surface movement through the steel pedestals installed on the slide body. Since the thickness of the overburden is more than 100 m, deep - seated movements in some part of the slope can not be ruled out.

Recommendations

The first phase of study supports to carry out monitoring through installed instruments. It is suggested to continue monitoring even after implementing remedial measures.