Construction method for connection section of air duct and station hall when obstacles exist on ground and underground

The invention relates to the technical field of tunneling methods or equipment, and discloses a construction method for a connection section of an air duct and a station hall when obstacles exist on the ground and underground, in the construction method, a wide and short tunnel lower than the bottom of an air shaft is arranged between the air duct and the station hall, and the air duct is excavated and connected from the station hall in the mode of being perpendicular to the air duct; the circulation sectional area of the connection section can be made to be large, the connection section can be widened along the air channel without being limited by obstacles, and the whole circulation sectional area is communicated with the air channel and the station hall. Meanwhile, construction of the connection section is carried out in two parts, one part is completed in advance along with steering excavation of a pilot tunnel on the lower layer of the air duct, the cross section of the main body part of the connection s