Composite foundation

The utility model discloses a composite foundation, including soft soil foundation layer, mattress layer and a plurality of pile body, its characterized in that: the mattress layer including flexible soil layer and the rigidity soil layer of lower floor on upper strata, the pile body include pile body and pile cover, the bottom surface of pile cover set up at flexible soil layer and rigidity soil layer juncture, the pile cover includes the bellied top of base and step form of cylinder shape, during flexible soil layer is thrust to step form arch, distance between a plurality of pile bodies is the third of pile body, and the bellied top of step form height is the twice of the base of cylinder shape. The utility model has the advantages of effect through this kind of flexible soil layer and rigidity soil layer for the mattress layer has certain bearing capacity, and the bottom surface of pile cover sets up the monolithic stability that utilizes the pile body at flexible soil layer and rigidity soil layer junctu