Abstract: Aiming at the problem of insufficient research on the deformation calculation of the secant pile at present, on the basis of considering the effect of the top beam, the p-y curve method is used to establish the deformation calculation model of the secant pile, and the formula for calculating the structural deformation of the secant pile is deduced. The finite difference method is used to solve the formula for calculating the deformation of secant pile structure. Based on the case of a deep foundation pit in Lanzhou, the results calculated by the proposed calculation method are compared with the results simulated by the PLAXIS 3D finite element software. The results show that:When calculating the deformation of secant pile, it is feasible to equivalent secant pile structure to underground diaphragm wall structure through stiffness equivalent principle.There is a cooperative deformation relationship between the top beam and the secant pile structure, and the top beam can control the deformation of the secant pile structure.Although the trend of the results calculated by the proposed calculation method is the same as that of the numerical simulation, there are some differences in the numerical value, which is due to the different constraint conditions of the bottom of the secant pile and the constitutive relation of the soil in the process of calculation and simulation.

Key words: deep foundation pit, secant pile, deformation, calculation method