Pile foundation negative friction reduction device

The pile foundation negative friction reduction device comprises a pile casing, a mounting frame and balls, the pile casing comprises an inner pile casing body and an outer pile casing body which are sequentially arranged on a pile foundation in a sleeving mode from inside to outside, the mounting frame is fixedly connected to the peripheral face of the inner pile casing body, and a communicating hole used for communicating the inner side and the outer side of the inner pile casing body is formed in the inner pile casing body; the balls are rotationally connected to the mounting frame, penetrate through the communicating holes and are used for abutting against the pile foundation, and the rotating axes of the balls are perpendicular to the axis of the pile casing. When the soil layer sinks, negative friction resistance is generated on the peripheral face of the outer pile casing, and the outer pile casing prevents the outer layer soil layer from influencing the pile foundation. Supporting force is provided fo