Support changing method and support changing structure of middle wall of foundation trench

The invention relates to a support changing structure of a middle wall of a foundation trench. The support changing structure comprises floor boards respectively arranged at all excavation division zones of the foundation trench, floor board reinforced steel bars, frame beams arranged at all excavation division zones of the foundation trench, and frame beam main reinforcement bars. Middle walls are arranged at among all excavation division zones of the foundation trench; and the end portions of floor boards support the middle walls to form a force transmission structure. One end of each floor board reinforced steel bar extends into the floor board and a connection segment is formed at the other end of the floor board reinforced steel bar; and the connecting segment extends to the middle wall and bends temporarily. To-be-poured frame beam zones are formed between the frame beams and the middle walls. One end of each frame beam main reinforcement bar extends into the frame beam and the other end is arranged in one to-be-poured frame beam zone in a reserved mode to form a connection segment extending into the to-be-poured frame beam zone; and straight threaded bushes are arranged at the connecting segments. When the middle walls are removed, the floor board reinforced steel bars are directly straightened to carry out overlapping and binding connection and connecting ribs are also arranged to realize overlap joint with the frame beam steel bars; and then a concrete run-through structure is poured. The formed structure has high quality; the efficiency is high; and the cost is low.