Rail transit existing station structural joint drainage structure and construction method

The invention belongs to the technical field of subway station construction, and particularly relates to a rail transit existing station structural joint drainage structure and a construction method.The rail transit existing station structural joint drainage structure comprises a first drainage ditch embedded into a concrete cushion layer above a structural joint, the bottom of the drainage ditch communicates with the structural joint, and the top of the drainage ditch is covered with a cover plate structure flush with the ground; two rows of supporting units used for supporting the cover plate structure are arranged between the top and the bottom in the drainage direction, and all the rows of supporting units are arranged at intervals. One end of the second drainage ditch is communicated with the first drainage ditch, and the other end is connected to a drainage pipe network; water leaked through the structural joint can be drained through the first drainage ditch, excessive accumulated water in the structur