抄録
This paper presents forensic investigations of earthquake induced failures during Sikkim 2011 Earthquake, India. Detailed field geotechnical observations and geophysical investigations have been carried out at selected locations affected by 2011 Sikkim earthquake. Field observation, drilling of boreholes with sample collection (DBS), surface wave testing by Multichannel Analysis of Surface Wave (MASW) method and Ground Penetrating Radar (GPR) survey have been carried out at sites having slope failures, settlement and structural failures. Three different failure cases: distressed pavement over a natural slope, a school building, and secretariat building failures are discussed with reference to the field tests carried out. GPR radargram showed the cracked portion of pavement and the depth of the cracks. DBS and MASW at school building show the presence of loose cohesionless soil layer below the top dense layer, which might have undergone cyclic mobility and hence resulted in a settlement and cracks in the floor slab. GPR investigation at Sikkim secretariat building showed that the building is constructed on a sloped ground, where one side is filled with soil (damaged side) and the other side is directly resting on the rock. The study highlights the possible reasons for local seismic wave amplification and the associated damage with the help of field investigation carried out.
