The Study And Application Of Negative Friction Of Pilefoundation Project

Considering the practical situation of the Yangshan deep water port project and negative friction problem of pile foundation project, combined with field prototype observation, a profound study is carried out for the calculation theory and estimation method of experiential formula, correlative project measures are also presented.The landside area of the Yangshan deep water port is consisted of large-area high fill soil which is short period project. Sheet-pile quay is adopted in the back of the dock to avoid the bad effect of landside area of high fill soil. The foundation of sheet pile is affected largely by negative friction. Due to the difference among calculation methods of the negative friction and obvious settlement, the effects of negative friction on the Yangshan deep water port project is complicated and must be dealt with appropriately. To grasp the influencing rule of negative friction, field prototype observation of sheet pile foundation slab and scientific free pile is carried out and many precious data are collected. Based on the foundations above, the analysis and calculation of the location of neutral point and negative friction on the pile surface are finished by finite element numerical simulation, on the other hand, the practical calculation method for negative friction of single pile is discussed by adopting approximate approach and method of effective stress in evaluating the location of neutral point and magnitude of negative friction, respectively. These two methods are proved to be reasonable and useful compared to the analysis result of prototype observed data. Furthermore, for the sake of optimization analysis, reasonable values of key parameters are presented according to the geological characteristic of the Yangshan deep water port project.Through a series of studies, the knowledge on key parameters such as distribution, magnitude and temporal variation of negative friction of structural pile foundation, and the location of neutral point is acquired, which is valuable and contributes largely to the subsequent construction of the Yangshan project.