It can be divided into rigid foundation and flexible foundation according to the material and force of the foundation. From the structural form of the foundation, it can be divided into strip foundation, independent foundation, raft foundation, box foundation, pile foundation, etc. The following introduces the structural characteristics of several commonly used foundations.1. Bar foundation:When the superstructure of the building adopts wall bearing, the foundation is set along the wall, and it is mostly made into a long strip, which is called a strip foundation or a strip foundation.2. Independent foundation:When the superstructure of the building adopts a frame structure or a single-storey rack structure to bear the load, the foundation is often a square or rectangular freestanding foundation, which is called a free-standing foundation or column foundation.3. Raft foundation: when the upper load of the building is large, and the foundation is weak, the use of a simple strip foundation can no longer meet the needs of foundation deformation, usually the wall or column foundation is connected into a piece, so that the load of the building bears on a whole slab to become a raft foundation.4. Box foundation: When the slab foundation is made very deep, the foundation is often changed to a box foundation. The box foundation is an integral structure composed of reinforced concrete slabs, roof plates and several longitudinal and transverse partition walls.5. Pile foundation:The pile foundation is composed of a foundation pile and a bearing platform connected to the pile top. If the body is completely buried in the soil and the bottom of the platform is in contact with the soil, it is called a low platform pile foundation.