Abstract:

In order to study the influence of shield cutting pile excavation on the new underpinned pile, taking a shield cutting pile project of Nanchang Metro Line 2 as background, the threedimensional solid model is established by using ABAQUS finite element software to analyze the change of new underpinned piles and bending moments. In the model, three kinds of working conditions, such as before cutting the old pile, just cutting off the old pile, and cutting off the old pile and driving forward a certain distance forward, are used to analyze the deformation and bending moment of the new underpinned piles. The rationality of the direct shield cutting pile excavation scheme is evaluated. The calculation results show that： （1） The maximum deformation of the underpinned pile perpendicular to the tunnel axis occurs at about 2.5 m above the tunnel, and the maximum deformation along the axis of the tunnel occurs at the top of the pile. （2）The maximum bending moment of the pile body appears in the depth range of the tunnel section, and the maximum value can reach above 600 kN·m. Therefore, the design of pile foundation is not only required to the verification of the bearing capacity of the normal section, but also the bearing capacity of the bending.

Key words: shield cutting pile, numerical simulation, underpinned pile, deformation, pile foundation design, pile bending moment