Deep foundation pit supporting structure and construction method

The deep foundation pit supporting structure comprises a prefabricated underground diaphragm wall, one face of the prefabricated underground diaphragm wall is attached to the inner wall of a foundation pit after excavation of the foundation pit is completed, a plurality of rows of anchoring through holes are transversely formed in the prefabricated underground diaphragm wall at intervals, and a grouting anchor cable is arranged in each anchoring through hole in a penetrating mode; one end of the grouting anchor cable is anchored on one side of the prefabricated underground diaphragm wall through an anchorage device; the anti-slide piles are embedded in a soil body outside the foundation pit at intervals, each anti-slide pile is of a reinforced concrete structure, the anti-slide piles correspond to each row of anchoring through holes, and one ends of the grouting anchor cables in the same row are jointly anchored in the same anti-slide pile. Compared with a pure continuous wall and anchor cable supporting mode