Pile foundation underpinning structure

The utility model relates to the technical field of pile foundation underpinning, and discloses a pile foundation underpinning structure which is arranged below an existing bridge pier, an existing bearing platform is arranged below the bridge pier, an underpinned pile is arranged below the bearing platform, the underpinning structure comprises an underpinning beam and an underpinning pile, the existing bearing platform is wrapped by the underpinning beam, and the underpinning pile is arranged below the underpinning beam. The two sides of the underpinning beam are supported by underpinning piles, pre-jacking bearing platforms are arranged on the tops of the underpinning piles, a connecting section is arranged between the underpinning beam and the pre-jacking bearing platform on each underpinning pile, and a jacking device is arranged on the connecting section. The pile foundation underpinning structure solves the technical problems that an underpinning pile foundation of an existing pile foundation underpinni