Subway station excavation process for determining foundation width based on foundation bearing capacity

The invention discloses a subway station excavation process for determining the width of a foundation based on the bearing capacity of a foundation, which comprises the following steps of: (1) excavating a pilot tunnel, and constructing a primary support; (2) a bottom longitudinal beam strip foundation is constructed in the lower pilot tunnel according to the corrected and calculated width of the bottom longitudinal beam strip foundation, and then a frame supporting system is constructed on the bottom longitudinal beam strip foundation; and (3) main body soil body excavation is conducted on the basis of the frame supporting system, and earthwork is excavated from top to bottom to the elevation of the middle floor slab. The method comprises the following steps: integrally analyzing a subway station structure by analyzing and researching the foundation bearing capacity of the bottom longitudinal beam of the cavern-column station, taking the foundation bearing capacity of the bottom longitudinal beam of the cave