Post-tensioning method unbonded prestressed anchorage pile structure and construction method thereof

The invention discloses a post-tensioning method unbonded prestressed anchorage pile structure and a construction method thereof. The post-tensioning method unbonded prestressed anchorage pile structure is characterized in that a drilling machine is used for forming a hole, after the hole is finished, a drilled hole and one or more spaced annular conical cavities along a pile hole are formed at the pile end in an extrusion expansion or rotary expansion mode, and then a steel strand with an anchorage device at the front end is placed in the hole; the steel strand extends to a hole opening all the time and is sleeved with a sleeve, the sleeve is filled with grease, the steel strand is completely soaked in the grease, then the hole is cleaned through a lower guide pipe, concrete is poured tothe position above the uppermost annular conical cavity, the rest pile hole piles are filled with soil or muck and the like, and the cavity becomes a disc body; and after the concrete reaches the preset strength, the steel st