Numerical simulation of negative skin friction on single pile in multiple layer deposits

The process of producing negative skin friction(NSF) is the energy transformation between the soil mass and piles,and researches on it can help to obtain further understanding of the NSF principles and to promote calculation accuracy.First,the deformation energy of piles as well as the external forces acting on them was discussed,and theoretical formulas were also deduced.Then,from the two aspects of energy balance and static equilibrium,the stress and strain of piles were analyzed,through which equilibriums equations were listed and related formulas were deduced.Next,considering that the shear strength of soil increased linearly with the depth,matrix expressions of energy balance and displacement coordination of pile element were given.Finally,by means of establishing linear simultaneous equation and getting iterative solutions,the NSF on single pile in multiple layer deposits,the axial forces and displacement of piles were calculated.Through programming an engineering example and comparing its results with in-situ data,conclusions were drawn: the calculated results were well agreed with in-situ data and the established program could simulate characters of the NSF on single pile.