The invention provides a rotary-digging combined
pile-forming construction method in complicated geological conditions. The method comprising the following steps of: firstly, positioning a
pile foundation; secondly, positioning a steel protecting
barrel; thirdly, sinking the steel protecting
barrel; fourthly, when the steel protecting
barrel penetrates through a boulder layer without encountering the boulder, sinking the steel protecting barrel to the design elevation by using a vibration hammer; fifthly, starting a rotary digging and drilling
machine to perform rotary digging and drilling at the inner side of the steel protecting barrel; sixthly, hoisting an impacting and catching hammer by a hoist, and downwards hammering and impacting the boulder by the impacting and catching hammer; seventhly, starting the rotary digging and drilling
machine to continuously perform rotary digging and drilling to the design elevation; eighthly,
fishing slag from the bottom of a hole; ninthly, checking and accepting a final hole; tenthly, aligning the skeleton of a steel reinforcement cage to the opening of the hole and slowly hoisting into the hole by the hoist; eleventhly, secondly cleaning the bottom; twelfthly, concreting; and thirteenthly, after primarily setting the concrete, lifting up the steel protecting barrel by the hoist. The method has the advantages of high safety and reliability, strong stratum adaptability and high construction progress and is suitable for the
pile foundation engineering in cities with complicated geological conditions.