Cover excavation top beam and temporary pile column structure for pile foundation underpinning and construction method

The invention discloses a cover excavation top beam and temporary pile column structure for pile foundation underpinning and a construction method.The cover excavation top beam and temporary pile column structure comprises a transverse supporting beam, a longitudinal supporting beam, a temporary pile column and an enclosure structure which are arranged around an existing pile foundation bearing platform structure, the existing pile foundation bearing platform structure is connected with the transverse supporting beam and the longitudinal supporting beam, and the two ends of the transverse supporting beam are connected with the enclosure structure; the two ends of the longitudinal joists are connected with the transverse joists, and the temporary piles are arranged between the existing pile foundation bearing platform structure and the enclosure structure. The invention further provides a construction method aiming at the structure, the design concept of'covering and excavation of the top beam and temporary pi