The rotary excavating cast-in-place
pile for the foundation pit comprises a
drill rod and a round plate, a round opening is formed in the round plate, the
drill rod is installed in the round opening, a drainage structure is installed outside the
drill rod, and the drainage structure comprises a cylinder, a
water pipe, a first round hole and a second round hole; a vertical hole is formed in the cylinder, the drill rod is installed in the vertical hole, the drill rod and the cylinder are inserted into soil, the cylinder is arranged outside the drill rod in a sleeving mode, the
water pipe is arranged between the cylinder and the drill rod, the first round hole is formed in the cylinder, and the upper discharging end of the
water pipe is installed in the first round hole. The drill rod drives the cylinder to drill into soil for construction hole forming, in the hole forming process, the liquid inlet end of an external pump body pumps out underground water in a formed hole through a water
pipe, the drill rod drives the cylinder to pump out the underground water into the formed hole,
cement paste is injected into the formed hole, the injected
cement paste is prevented from being combined with the underground water, and the
viscosity of the injected
cement paste is reduced; therefore, a firm rotary excavating cast-in-place
pile is formed.