Analysis Of Bearing Behavior Mechanism And Settlement Calculation Of Super-long Piles

Super-long piles are widely used with the construction of high-rised buildings and large span bridges, however the research and theory of super-long piles is fall behind its applications.FEM parameters is req uired from FEM sim ulating the in-situ data, and th e working modes of the shaft resis tance and tip resistance under the working load and the ultimate load was also obtained from the FEM sim ulating. Some conclusion can be summarized from Q ?s curves, distribution mode of shaft resistance and ratio of tip resistance from load on pile top.It is the fact that the effective length can be used in Super-long piles from analyzing the bearing capacity of dif ferent length of piles having the sam e diameter with FEM Method. Soil conditions can influence on the effective length of Super-long piles.Measured data shows that: the friction on the upper part of super-long piles shaft resistance develops first under the worki ng load, the distribution of pile shaft resistance is closed to two segm ents or three segments linear distribution. However, Geddes stress solution which based on Mindlin solution assumes that the distribution of the pile shaft resistance is combination of triangle and rectangular distribution, and this is still adopted to calculate the additional stress caused by the friction of piles at the present Code.The stress solution of two segm ents and three segm ents linear distribution is deduced by com bination of Geddes soluti on. The comparision analysis of the distribution modes suggested in this pape r and the Geddes solution shows that: the additional stress beneath the piles of Gedde s stress solution is signif icantly greater than that of the m ethod suggested in this paper when the number of the piles is not very large. The settlem ent ratio of Geddes solution is gr eater than th at of method suggested in this paper, so the Geddes so lution exaggerates the interaction of group piles.The vertical additional stress of the two distribution modes differ relatively small when the number of group piles are lar ge and the distance of the pile center is dense. Examples calculation shows that: the resu lts obtained by the m ethoed suggested in this paper are closer to that of observed data when other parameters are the same.