Abstract:

The load-settlement relationship, the composition and ratios of pile head settlement of overlength large diameter piles are analyzed with FEM in different situations of geometric parameters. The following rules are obtained according to the calculated results: the big settlements are needed to bring the ultimate bearing capacities of overlength large diameter piles into play; and the required settlements increase with increase of length-diameter ratios (L/D). The deformation of over-length large diameter piles are mainly controlled by the compression deformation of pile shafts; the proportion of pile tip settlement is low; and there is a function relation between the proportion of each composition of settlement and length-diameter ratio. For the over-length large diameter piles with L/D=50-83, the proportions of compression deformation of pile shafts are 65.2 %-71.83 % in the ultimate states; and the proportions of settlements caused by the pile end loads are 15.7 %-9.72 %; under the working load states, the proportions of compression deformation of pile shafts are 66.1 %-72.5 %; and the proportions of settlements caused by the pile end loads are 10.8 %-3.9 %.

Key words: overlength large diameter pile, FEM, deformation characteristics, length-diameter ratio