Construction method of cylindrical slurry core pile for retaining and protecting foundation pit

The invention relates to a method of a cylindrical slurry core pile for retaining and protecting a foundation pit, belonging to a foundation pit construction method and the field of machines in municipal engineering. In the method, before dredging the foundation pit, cylindrical slurry core piles which are formed by field slurry molding bodies which are connected by center pre-setting hollow core materials and outer walls are arranged along the two wall bodies of the foundation pit at interval, that is, the core materials are pre-arranged and located in a pile hole which is drilled mechanically through the location of the pile hole, the hole between the core materials and the pile hole is injected with colloidal slurry, after the slurry is coagulated, the slurry and the core materials form single cylindrical slurry core pile; according to the design, after retaining and protecting the rows of the slurry core piles at the two sides of the wall body of the foundation pit, the foundation pit is dredged, the earth is backfilled after carrying out the construction, the pre-setting core materials are pulled out from the pile, and the pile hole is backfilled with sandy soil; the method is a simple retaining and protecting method of hollow cylindrical piles aiming at the earth with good quality, the mechanical hole-forming is adopted, the occupying area is small without big dredging construction, the environment is beneficial to being protected, the core materials of steel tubes can be used repeatedly, the resource is saved, and the method has wide application range.