Method for forming pile foundation of karst cave in karst area

The invention relates to the field of pile foundation construction, in particular to a pile forming method for a karst cave pile foundation in a karst area. Comprising the following construction steps: drilling a full pile casing to a top plate position of a first-layer karst cave section by section through a rotary drilling machine; then drilling is continued, concrete backfilling is conducted on the karst cave in the pile foundation, and drilling is continued after the concrete strength is not lower than 10 MPa after backfilling; and after the depth count of the rotary excavating drill reaches the designed depth, cleaning the hole by adopting a slag salvaging drill to obtain the formed hole. And then concrete is poured, and the top-layer full pile casing is screwed out section by section till all pouring is completed. The soft stratum is stabilized firstly, then the karst cave is cleaned, and the karst cave is subjected to backfilling pretreatment in cooperation with concrete, so that the collapse risk of t