Seismic Analysis of Multi Layered Ground Considering Damping Characteristics of Cohesive soil = Seismic Analysis of Multi Layered Ground Considering Damping Characteristics of Cohesive soil

다국어 초록 (Multilingual Abstract)

A Cyclic viscoelastic-viscoplastic constitutive model for clay is incorporated into an effective stress based seismic analysis to describe damping characteristics of clay layer to sand layer during earthquake. The seismic response against fore-shocks, main shock as well as after-shocks of 1995 Hyogoken Nambu Earthquake is analyzed in the present study. Acceleration response in both clay layer and just upper liquefiable sand layer are damped due to viscous effect of cohesive soil. In the case of main shock and the following after-shock that occurred within less than 9 days after main event, acceleration responses near at ground surface are damped due to the developed excess pore water pressure, while that at ground surface are amplified in other cases. Using the viscoelastic-viscoplastic model for clay, time history of acceleration response in upper liquefiable sand can be well calculated, in particular in the range of micro-tremor process after main seismic motion.