Three-Dimensional Numerical Analysis Of Rammed Expanded CFG Pile Composite Foundation Mechanic Behaviors

The time of the CFG pile composite foundation research is about 20 year, since the first research to it in 1988.In these years,because this technology has the quickly construction speed, the time of construction is short, the quality easy to control and the building cost of projects is low, it has received the engineering's high praise and was widely used in foundation treatment.This article analysised and discussed the force characteristic of it base on the the CFG pile compound ground treatment project of Nanchong Northern Sichuan Province Medical School hospital buiding. The analysis method used by this article is experiment data analysis at the first step. Then creat three-dimensional model based on the first step to analyse the rammed expanded CFG pile. Afterward uses the hyper-trend surface by numerical simulation's data the analysis method to study the influence which caused by many factors simultaneously change to the rammed expanded CFG pile.First, it was studied that the axial force transmission and the load shares ratio of pile and soil by the experiment data analysis. And it was Selected the short-term observation experiment's five piles to carry on the analysis. Through compare the load shares ratio curve of pile and soil to straight line found that except one pile having big error at Initial time all pile's load shares ratio curve are similar to straight line. It indicated that its linear characteristic is quite obvious and could use the straight line to replaces the cuve and the slope ratio of it is irrelevant with its position.Secondly, execute simulation using numerical simulation's method to simulate the construct-location experiment. By the way to changes each influence parametric analysis its influence to the pile axial force, the load shares ratio of pile and soil and negative friction force. Through the analysis found that the pile a axial force maximum value basically increases at the linear relations with the pile radius, but because the stratum is different, at different positon pile's linear relations are dissimilar and its slope ratio is not equal.Finally, useing multi-dimensional statistics' hyper-trend surface analysis principle,created a hyper-trend surface with the single factor's numerical simulation result. Then analised the CFG pile's force characteristic at the multi-factors affects, to observe the interaction of different factors. The analysis indicated that the pile length and the pile radius are big influence factors to the pile axial force. When mattress thickness is big it has small infuence to the pile axial force. The pile rigidity has small inflence to the pile axial force. by adjustment the pile length and the pile diameter may obtain the the minimum value of the pile axial force.