Bore forming device of soft soil stratum cast-in-situ bored pile and construction method thereof

The invention provides a bore forming device of a soft soil stratum cast-in-situ bored pile and a construction method thereof. The bore forming device comprises a slag barrel, a drill pipe which is inserted in the slag barrel and can move in the axial direction of the slag barrel, and a driving motor used for driving the drill pipe to rotate in the circumferential direction of the drill pipe. A cutting part used for being cut into a bore to-be-formed position in a soft soil stratum is arranged at the bottom of the slag barrel, and the drill pipe and the slag barrel are coaxially arranged. A spiral bit is coaxially connected to the bottom end of the drill pipe, the outer diameter of the spiral bit is matched with the inner diameter of the slag barrel, the spiral bit rotates in the circumferential direction under driving of the drill pipe. According to the bore forming device, bore forming construction of the soft soil stratum cast-in-situ can be quickly achieved, meanwhile, the disturbance to a bore wall soil