The researches on rigid piles were mostly focused on their bearing capacities;and few people studied their deflections.So a method for determining rigid pile positions is put forward;and thus the displacement of any point on pile

the position of rotation center and the deflection angle of rigid pile can be obtained from the lateral displacements of any two points on rigid pile.The rigid piles embedded in silty clay are tested and analyzed numerically.It is found that the rotation center falls sharply firstly

then descends slowly and finally tends to be stable with displacement and load.Embedding parameters of piles and mechanical parameters of soil have few effects on the varying laws of the position of rotation center with lateral loads.The deflection angle of rigid pile increases linearly with loads on the whole.By comparison

it is found that the ultimate positions of rotation centers obtained from test and numerical analysis are consistent basically with those from some limit subgrade reaction methods.