P-Y Curves Of Laterally Loaded Single Battered Piles In Sand And Its Application

Generally,a pile will carry much larger axial loads than lateral loads.Through battering,a designer expects to transfer a portion of the lateral load to axial load,thereby increasing the lateral capacity of a pile group.The axis of oblique pile is not perpendicular to ground plane,its surrounding soil stress field is non-axisymmetric distribution,which makes the bearing deformation character of battered pile more complex than straight pile.Therefore,it is of great practical significance to study battered pile.The determination of the horizontal bearing capacity and the internal force for the battered pile is an important subject to be study in the engineering practice.Besides the use of a little amount of field tests,p-y curve approach has to consider the characteristics of the interaction between nonlinearity and plasticity of soil and pile.It becomes a major method for analysis of pile behavior under horizontal load,and how to construct the p-y curves is the key to use p-y curve approach.Firstly,in order to obtain the p-y curves of laterally loaded piles in sand,a series of model tests including four battered piles and one plumbed pile embedded in medium-dense dry sand were firstly conducted and the relationship between the soil resistance,p,and the lateral displacement,y,of pile shaft was obtained by fitting the model test results.In addition,the stress-strain(??~?)curves for the sand used in the model tests were gotten based on the tri-axial compression test.Then,a new p-y curve for laterally loaded batter piles was proposed according to the relationship between the dimensionless p-y expression and the dimensionless ??~? curves,the methods to determine parameters in the p-y curve were also given.Then,used the results of five battered piles embedded in medium-dense dry sand under lateral load tests and other investigators' research results to analyze the limitingforce per unit length profile and soil resistance along pile.The influence regularity of pile inclination to p-y curves for batter piles was analyzed and a hyperbolic expression for battered piles under lateral loads was used to established a p-y curve approach for single battered piles.Finally,the comparisons between the calculated results base on the p-y curve proposed herein and the model test results in this paper or the centrifuge model tests reported in documents demonstrated that the p-y curve proposed for laterally loaded batter piles was reasonable and can be used to describe the complex compression and shear behavior between the inclined piles and the surrounding soils.Then the p-y curves were used to analysis the behaviors of the inclined piles under different conditions and it was found that the effect of constraint condition of pile top,vertical load on pile top and ratio of relative stiffness of pile to soil was relatively obvious.