| dc.description.abstract | In recent years, pile foundation develops very quickly, especially in high buildings and skyscraper. There are kinds of methods to determine the ultimate bearing capacity. The pile loading test is the most useful, but it is not economical and takes long time. Therefore, numerical analysis is suitable for simulation. The two dimensional axisymmetric analysis can’t fully simulate the real condition, it can only reflect the simplified condition of plain strain. Therefore, this study uses FEM software ABAQUS to analyzes the three-dimensional simulations. First, simulate the single bored pile, then apply the setting and mesh into pile groups. Second, set the three major factors (a) spacing (b) pile number (c) settlement to understand the relations with pile group effect. The analytic results evaluated from the FEM software ABAQUS show that (1) in sand and clay layer, the cause of group effect comes from the stress overlapped by piles. Group efficiency increases with the spacing increases, it decreases with the pile number increases. Group efficiency in sand has obvious behavior with pile settlement increases. But in clay, it only occurs when the load approaches to ultimate capacity. (2) When the spacing is 2D, pile group failure behavior will become to the whole block failure. (3) In sand, group effect is very obvious in the earlier stage of loading. The center pile’s bearing capacity will increase by the pile-soil pressing. (4) In clay, the group efficiency is small and almost the same before the pile settlement reaches 10cm. And the effect of range is larger than in sand.
| en_US |