Abstract:

Piles supporting bridge abutments on soft clay may be loaded laterally from horizontally soil movements induced by the approach embankment. 3D finite element modeling of piled bridge abutment is set up to explore the behavior of piles induced by embankment load which is compared well with the data from the site monitoring. The results indicate that the bending moment of piles and settlements of bearing platform calculated are consistent with the data from the site monitoring. The curves of the maximum bending moment plotted against the average stress applied by the embankment in the middle pile row and the rear pile row are double broken lines which are consistent with what Stewart, D.P. suggested. However, the average stress corresponding to the threshold (at the intersection of the two lines) do not occur at the same embankment load which are about 3.34 times weighted mean ccu of layered strata in the middle pile row and about 2.22 times weighted mean ccu in rear pile row. The curve of the maximum bending moment plotted against the average stress in front pile row is linear. The deflection of the pile cap plotted against the average stress applied by the embankment doesn’t agree with the curve Stewart, D.P. suggested. The curve obtained in the paper is nonlinear and can be divided into two portions. The maximum bending moment of the front pile row is developed at the upper portion of the clay layer rather than near the pile cap, but that of the rear pile row is developed at the upper portion of the clay layer under low embankment load and then shows the maximum value at the pile head under high embankment load.

Key words: soft soil, piled bridge abutment, embankment, site monitoring, finite element method