An open excavation construction method for expanding excavation of a
station on a metro interzone shield tunnel foundation method includes the steps that uplift piles, wall columns, a base plate, a middle stand column foundation and transverse supporting beams between the wall columns are constructed in a transverse channel, wherein the base plate is connected with the bottoms of the wall columns, water prevention treatment is conducted, and the wall columns and duct pieces are connected, so that a sealed
stress system is formed; soil over the tunnel is subjected to grouting reinforcement, an excavation retaining structure of a
station body foundation bit is built, and the top end of the structure is connected with an external campshed or an underground diaphragm wall through a connection beam; slopes are supported through a composite
soil nailing supporting technology, foot locking supports are erected at the
pile foots, after excavation is conducted on the bottom of a foundation pit, residual duct pieces are removed, connection beams between the wall columns are constructed, and the connection beams are firmly connected with the duct pieces; the transverse
support system is constructed. The method is reasonable, feasible and high in maneuverability. By means of application of the method, great
economic benefits,
social benefits and environmental benefits are achieved. The method has significant
engineering application value and development prospects.