Cofferdam device for floating pebble stratum and construction method of cofferdam device

The invention belongs to the technical field of bridge construction, and particularly relates to a floating pebble stratum cofferdam device and a construction method thereof. When cofferdam construction is carried out in a floating pebble stratum, steel sheet piles and steel jacket boxes cannot efficiently reach mounting positions, so that the construction process is complex, and the construction efficiency is low. According to the floating pebble stratum cofferdam device and the construction method of the floating pebble stratum cofferdam device, due to the fact that the construction method that the cofferdam is placed in the foundation trench is adopted during cofferdam construction, the cofferdam can reach the installation position easily, and the problem that the floating pebble stratum is prone to cracking and collapsing in the construction process to cause construction accidents is solved; excavated soil and stones can be repeatedly used for backfilling after being screened, and a good supporting effect