Construction method for sinking and soil taking of ultra-large open caisson

The invention provides an ultra-large open caisson sinking soil taking construction method which comprises the steps that an open caisson core area and a remaining area are divided, an open caisson is divided into a plurality of areas, a soil taking area and a soil taking blind area of a well hole are determined, the soil taking depth of the soil taking area of the well hole is determined, layered and zoned soil taking is conducted on the whole section of the open caisson, and a mud suction hole and a water jetting hole are reserved through an open caisson structure. High-pressure jet water flow is adopted to destroy a blind area soil body, and the soil sampling progress is adjusted based on open caisson foundation posture monitoring and structural stress monitoring data. Full-section zoned and layered soil sampling is performed according to the symmetry principle, stable sinking of the open caisson foundation is facilitated, the good sinking state of the open caisson is guaranteed by setting the soil samplin