Prefabricated subsurface structure under foundation trench open cutting condition and construction method for prefabricated subsurface structure under foundation trench open cutting condition

The invention discloses a prefabricated subsurface structure under the foundation trench open cutting condition and a construction method for the prefabricated subsurface structure under the foundation trench open cutting condition, and relates to construction of subsurface structures in constructional engineering. The structure comprises a base plate cushion layer, a cast-in-place base plate, a superposed beam, a superposed plate, a superposed wall and a prefabricated center post; the superposed wall and the prefabricated center post are supported by the cast-in-place base plate and solidified with the cast-in-place base plate; and the superposed beam comprises a prefabricating part and a cast-in-place part. The construction method for the prefabricated subsurface structure under the foundation trench open cutting condition comprises the steps of (1) foundation trench open cutting, wall anchor support or wall anchor timbering are carried out; (2) the base plate cushion layer, a base plate coiled material waterproof piece and the cast-in-place base plate are constructed; (3) a tile molding bed is constructed; (4) mortar leveling is carried out on the outer side of the tile molding bed, and waterproof coiled materials are paved; (5) the superposed wall is lifted; (6) concrete cast-in-place is carried out between the superposed wall and the tile molding bed; (7) the prefabricated center post is lifted; (8) a prefabricated part of the superposed beam and a prefabricated part of the superposed plate are lifted; (9) cast-in-place is carried out on a superposed beam plate and column and wall node concrete; and (10) a top plate is wrapped with the waterproof materials, and top earthing back filling is carried out. The prefabricated subsurface structure has the beneficial effects of saving the working period and cost, the whole part is wrapped with the waterproof materials, the waterproof performance is guaranteed, and application and popularization are convenient.