UHPC-NC composite pile foundation and construction method for power transmission tower in saline-alkali area

The invention discloses an ultra-high performance concrete (UHPC)-normal concrete (NC) composite pile foundation and a pile forming method thereof, belongs to the field of power transmission line tower foundations, and is suitable for strongly corrosive salinized soil areas or geological condition areas with obvious dry-wet and freeze-thaw alternate action. The foundation comprises a foundation main pile penetrating through a soil layer to a supporting layer, and a prefabricated UHPC outer sleeve, wherein the portion, below the bottom of the UHPC outer sleeve, of the foundation main pile is ofa columnar structure, and the outer side face of the section, making contact with the sleeve, of the foundation main pile changes along with the shape of the inner wall of the sleeve. Compared with the traditional anti-corrosion measures, the UHPC-NC combined pile foundation has the advantages that under the same geological conditions and the same external load effect, on the basis of excellent material performance of UH