Cast-in-situ bored pile structure for karst area

The utility model relates to a cast-in-situ bored pile structure for a karst area. The cast-in-situ bored pile structure is characterized in that the cast-in-situ bored pile structure mainly comprises a cast-in-situ bored pile, a bag grouting body and pre-stressed anchor cables; clay and rubble mixtures are backfilled at the position of an original karst cave; the top of the cast-in-situ bored pile is provided with a pile top expanded pile body, and the bag grouting body is arranged at the position of the karst cave; an extrusion and expansion reinforcing cage is arranged in the bag grouting body; pre-stressed anchor cable holes are formed in the periphery of the cast-in-situ bored pile, and the pre-stressed anchor cables penetrate through the pile top expanded pile body. The cast-in-situ bored pile structure has the advantages of being high in construction speed, low in manufacturing cost and the like; through cast-in-situ bored pile action mechanism changing and single-pile bearing capacity increasing, the purpose of reinforcing a foundation is achieved.