Abstract: X-section cast-in-place pile (XCC pile) can save concrete usage under the same pile perimeter. However, there are little relative theoretical studies focusing on the lateral load reaction mechanism of the surrounding soil of XCC pile. The XCC pile holes are mapped on the unit circle using the conformal mapping of complex function method, and the plane strain solutions of stress and displacement distribution of surrounding soil of XCC pile under lateral load calculated by plane complex variable elasticity method are obtained. Then, the surrounding soil of pile are assumed as a series of independent springs, and the stiffness coefficients of the springs can be calculated by the plane strain solution in this paper. Pile deflection and internal force of XCC pile under lateral load can be calculated by using differential equations of the Euler-Bernoulli beam. The reliability of the theoretical calculated method built in this paper is verified by comparative analysis with the plane strain solution of the circular piles under lateral load obtained by Baguelin. Finally, one example is analyzed, and the results are compared with numerical calculated results. The results show that the reaction mechanism of the surrounding soil of XCC pile under lateral load can be simulated very well by this method, especially with small lateral load condition.

Key words: X-section cast-in-place pile, lateral load, soil displacement field, conformal mapping, analytical solution