Seismic response of pile-cap system installed in inclined soft clayey ground

In order to investigate the seismic behavior of pile-cap system installed in inclined soft clayey ground, a series of 1-g shaking table model tests were conducted on a 2 x 2 pile-cap system installed in an inclined kaolin clay bed. The test results suggested that the inclined clayey ground could considerably amplify the seismic ground motions, especially at pile cap and slope top; the frontal piles nearer to the slope top were found to experience evidently larger bending moments than the rear piles, suggesting that much larger amounts of downward thrust during seismic shakings were shared by the frontal piles, exhibiting a shadowing effect in the pile group. Additionally, a suite of three-dimensional (3D) finite element (FE) analyses were performed to systematically study the factors of inclination angle, horizontal seismic intensity, pile flexural rigidity and incorporation of vertical shaking on the seismic response of pile. It was found that, with the increasing horizontal seismic intensity or decreasing pile flexural rigidity, the piles could experience severe structural damages, which tended to be more significant with the increasing inclination angle; the influence of incorporating vertical shaking had a similar effect but in a much minor manner, suggesting that the horizontal shaking is more critical influencing the stability of the whole system. The findings obtained from this study can provide valuable reference for the seismic design and relevant risk assessment of piles constructed in inclined clayey ground.