Analyses Of The Vertical Bearing Behavior Of Group Pile Foundations Under Complicated Geological Conditions

Geological conditions for pile-raft foundation are generally quite complicated, but the soil complexity is considered seldom in national foundation design codes, and the researches on the effect of bearing behaviour of group piles due to complex geological conditions is very few. In this paper, based on a three dimensional nonlinear numerical model of the coupled finite element—infinite element—interface element, a program written in MATLAB was used to analyze the bearing and deformation mechanism of pile-raft foundation under soil-layers with inclining interface, changing soil-layers and changing rock-socketed length. At the meantime research on the theory of load-transfer mechanism of piles was done in view of soil conditions.So, the main purpose of this paper is to deal with the load-transfer mechanism of group piles under complicated geological conditions.There are two main goals in this paper; one is to make a study of the bearing behaviour of group piles under complicated geological conditions. And to probe in the applicability of current design rules and another is to study the load-transfer mechanism of group piles based on the complicated soil conditions.The researches indicate that the definite variability of bearing behaviour of single pile is shown but the entirety of bearing behaviour of group piles is obvious. When the group piles carry the normal load and the distance between piles is normal. In general, there is little affect on the general bearing heavier of group piles from the complicated geological conditions but the effect on the corner pile should be noticed especially in the condition of changing rock-socketed. The rock-socketed pile has conclusively rock-socketed affect, and when rock-socketed length achieves a certain value, increasing length will not influence bearing capacity.