Rapid construction method for ultra-large rectangular continuous open caisson underground station in soft soil stratum

The invention discloses a rapid construction method for an ultra-large rectangular continuous open caisson underground station in a soft soil stratum, which comprises the following steps of: dividing a continuous open caisson into seven open caisson sections, sequentially naming the open caisson sections as open caisson sections 1-7 from front to back, manufacturing each open caisson section for four times and sinking for two times, and correspondingly completing manufacturing of a main body of the open caisson section for one time; the sinking of the two sections of main bodies of the open caisson is correspondingly completed through one-time sinking, the continuous open caisson is divided into three stages for construction, the first stage is that the seventh open caisson moves in advance, the second stage is that the first, third and fifth open caissons follow up after meeting conditions, the third stage is that the second, fourth and sixth open caissons are constructed, and finally connecting sections bet