Device for carrying out secondary hole cleaning on cast-in-place pile by expanded pipe orifice and hole cleaning method

The invention discloses a device for carrying out secondary hole cleaning on a cast-in-place pile through an expanded pipe orifice. The device comprises a high-pressure gas tank, an air compressor and a gravel filter; the high-pressure gas tank is connected with the air compressor through a connecting pipe; a control valve is arranged on the connecting pipe; the high-pressure gas tank is connected with a gas pipe mounting device through a second hose; a three-way structure is arranged on the gas pipe mounting device; the gas pipe mounting device comprises a fixed pipe; the fixed pipe is sleeved with a three-way structure and comprises a main pipe and a branch pipe arranged on the main pipe; the two ends of the main pipe are matched with a choke plug and a pouring guide pipe respectively; the pouring guide pipe is provided with an adjusting device which is matched with the pouring guide pipe to ascend and descend; a first hose connected with the fixed pipe is arranged in the pouring guide pipe; the bottom of t