Dynamic centrifuge model tests on an unconfined soil foundation

A series of centrifuge shaking table tests on soil deposits are conducted under gravitational fields of 50gat the Institute of Geotechnical Engineering in Tsinghua University. The tests include 1 sand deposit model, 1 clay deposit model and 2 layered deposit models. They are performed using a laminar shear box with plan dimensions of 0.5 m and 0.2 m respectively, and the test system is subjected to strong ground motions, Kobe waves and Parkfield waves. Partial test results are presented, including acceleration responses, Fourier spectra of accelerations, amplification factors of peak accelerations and shear stress-strain histories. The test results indicate that the acceleration responses vary in different types of soil deposits. The amplification factors increase with the decreasing depth in low frequency. And the shear stress-strain histories show discrepancy in sand and clay deposits.