Depth modified sludge column combined pile composite foundation and construction method thereof

The invention belongs to the technical field of civil construction engineering, and particularly relates to a deep modified sludge column combined pile composite foundation and a construction method thereof. A pile body is mainly composed of a deep modified sludge column, and the center of the pile body is provided with grout gravel; gravel can overflow out of the pile body, a drainage channel is provided, the function of reinforcing peripheral under-consolidated soft soil is achieved, post-construction settlement can be effectively reduced, and the bearing capacity of a composite foundation can be effectively improved; the injected slurry can fill pores of the sand and stone and enter peripheral pores through the sand and stone channel, so that the sand and stone, the deep modified sludge column and the nearby soil body are solidified into a whole; the deep modified sludge column is prefabricated by modifying waste sludge, has a self-embedding characteristic, is energy-saving and environment-friendly and is