The invention relates to a
cofferdam rapid construction method capable of effectively avoiding back silting through firstly supporting and then piling, and belongs to the technical field of
cofferdam construction.The
cofferdam rapid construction method includes the steps that on the basis of an existing firstly-supporting method, a part of construction platforms are firstly dismantled, a part of steel casings are heightened, a part of cofferdam steel
pipe piles are inserted and driven, desilting is conducted in a cofferdam to be 0.5 m below the designed elevation of an inner support, and the remaining construction platforms are dismantled; cofferdam inner supports are assembled; a hanging
system is installed, a cofferdam inner support is lowered, the cofferdam is closed, and desilting is conducted to the bottom elevation of bottom sealing concrete; water is pumped in the cofferdam, bottom sealing concrete is poured, a
pile casing is
cut, and a
pile head is chiseled; and the bearing platform is constructed, after the upper-layer bearing platform reaches the design strength, the upper-layer inner support is dismantled, and the
tower base is constructed. During construction, part of steel
pipe piles are firstly inserted and driven to block most of back silting, favorable conditions are created for lowering an inner support in advance for cofferdam first-supporting method construction, and the problem that the construction period and the construction quality are affected due to the fact that
sludge with large thickness and high flowability enters the cofferdam in the prior art is solved.