Plugging structure for downcast tube well and construction method thereof

The invention belongs to the technical field of building construction, and particularly discloses a downcast tube well plugging structure which comprises a tube well body, a plugging blind plate A, a plugging blind plate B, an internal steel cover plate, a top steel cover plate, a fixing assembly and a pressing assembly. The blocking blind plate A is located on the inner side of the tube well body. A sealing ring used for improving the sealing performance is arranged on the outer side of the blocking blind plate A. A top blocking barrel is fixedly arranged on the top of the tube well body. The blocking blind plate B is located on the inner side of the top blocking barrel, and a limiting ring is fixedly arranged on the inner side of the top blocking barrel. A fixing assembly is arranged on the inner side of the top steel cover plate, and a pressing assembly is arranged on the blocking blind plate A. The plugging blind plate A and the plugging blind plate B in the top plugging barrel are pressed and fixed throu