Effect of the strengthening area and the slope rate on bearing and deforming behaviors of CFG pile-geogrid composite foundations

Abstract

In order to study the effect of the strengthening area and the slope rate on bearing and deforming behaviors of CFG pile composite foundations, centrifuge test with a similarity ratio of 1:80 and numerical simulation were conducted. The results show that the vertical displacement has a significant increase during embankment fill period and a slow growth during the placement and operation periods. With decreasing the strengthening area, the increasing trend of the vertical displacement with a slope ratio of 1:1.5 is greater than that of 1:1.75, which indicates that a steeper slope results in more sensitivity of the strengthening area. The horizontal displacements at the toe of the slope and 5 meters away from the toe of the slope are greater than those at other places. When the strengthening area decrease, a anti-bend point of the horizontal displacement at the toe of the slope occurs at the soil interface, and the anti-bend rate increases with decreasing the strengthening area. Under the same load, the stress on the pile top in a half strengthening composite foundation is greater than that in a whole strengthening composite foundation, but the earth stress between piles shows a opposite pattern. The pile-soil stress ratio shows a increase trend with the decrease of the strengthening area with a same slope rate.