Centrifuge Modeling of the Seismic Behavior of Soft Clay Slopes

Abstract

This paper presents the experimental results and analysis from two centrifuge experiments that simulated the seismic response of a gentle slope in soft clay. The two models consisted of a three-degree and a six-degree slope in soft clay, respectively, which are representative of typical slopes found on marine seabeds on the continental margins. The models were built in a laminar container in order to reproduce infinite slope boundary conditions. In-flight characterization investigations consisting of T-bar tests and air hammer tests were performed to obtain undrained shear strength profiles and shear wave velocities at various depths, respectively. A suite of earthquakes was applied, including sinusoidal waves and scaled real motions, in order to observe the response of the models in terms of the propagation of shear waves and the generation of lateral displacements at various depths in the slopes. The results showed that the model preparation approach ensures the repeatability of the experiments, enabling the evaluation of the impact of the slope angle on the seismic response of the gentle slopes studied. On average, the permanent displacements measured at the surface of the six-degree slope were three times greater than those measured at the top of the three-degree slope. In these slopes, nonlinear effects were observed in terms of the peak ground acceleration (PGA) that depended both on the slope angle and the intensity of shaking.