Underground diaphragm wall embedded steel enclosing purlin plug system and construction method thereof

The invention relates to an underground diaphragm wall embedded steel enclosing purlin plug system and a construction method thereof. The end expanded sections of subway station foundation pits have lots of internal and external corners, most of supports are diagonal bracings, a stress is complicated, and the deforming control difficulty of the foundation pits is large. Vertical force transfer steel plates perpendicular to steel enclosing purlins are arranged on the outer sides of underground diaphragm walls of the steel enclosing purlin ends. Steel enclosing purlin embedded steel plates are arranged on the surfaces of the underground diaphragm walls on the outer sides of the force transfer steel plates, shear-resistant anchoring ribs perpendicular to the steel enclosing purlin embedded steel plates are arranged in the underground diaphragm walls on the inner sides of the steel enclosing purlin embedded steel plates, the outer sides of the steel enclosing purlin embedded steel plates are provided with horizon