Geotechnical investigations of weathered slopes in muzaffarabad area after the 2005 Kashmir-earthquake

Muzaffarabad is situated close to the epicenter of 2005 Kashmir-Earthquake and many shallow landslides occurred during and after the earthquake. Natural breakdown of seismically-disturbed soft rocks due to weathering is a widespread ongoing phenomenon originating numerous fresh landslides and debris flows. For this reason, seismic refraction surveys, portable dynamic cone penetration tests, Schmidt hammer tests and sampling of residual soils were done in Muzaffarabad outskirts. The analysis of refraction surveys and penetration tests depicted the presence of shallow (0.5-1.5m) and highly weathered material with S-wave velocities in the range of 180 to 300 m/s. Rebound number was as high as 50 for exposed intact rocks and less than 10 at weathered surfaces. The strength and stiffness parameters determined from drained torsional shear tests seem to be largely affected by the sensitivity of soil grains to disintegrate upon saturation. The data presented in this paper can be supportive to practicing engineers for better understanding of the mechanical properties of weathered material for geotechnical analysis and design.