The invention relates to the technical field of
tunnel construction, in particular to a
pile foundation
underpinning construction method based on an
immersed tube connecting section, and the construction method comprises the following steps: S1,
underpinning piles are constructed on two opposite sides of an underpinned
pier pile, and the
underpinning pile on one side of the underpinned
pier pile penetrates through a to-be-constructed area of a mid-partition wall; s2, an underpinning bearing platform is constructed on the top of the underpinning pile; s3, an underpinning beam is constructed based on the soil layer supporting formwork, and a vertical gap is formed between the underpinning beam and the underpinning bearing platform; s4, a jacking
assembly is installed in a vertical gap between the underpinning bearing platform and the underpinning beam, the jacking
assembly is used for jacking the underpinning beam, and the part, located below the underpinning beam and interfering with the
immersed tube connecting section, of the underpinned
pier pile is dismantled; and S5, an
immersed tube connecting section is constructed below the underpinning beam. According to the pile foundation underpinning construction method based on the immersed tube connecting section, the distance between the adjacent underpinning supporting assemblies can be reduced under the condition that an internal channel of the immersed tube connecting section is not occupied, and therefore the maximum
bending moment and deflection of the underpinning beam are reduced.