Foundation refers to the soil or rock mass that supports the foundation under the building. As a building foundation, the soil layer is divided into rock, gravel soil, sand soil, silt soil, cohesive soil and artificial fill. There are two kinds of foundations: natural foundation and artificial foundation (composite foundation). Natural foundation is a natural soil layer that does not need to be reinforced. Artificial foundation needs artificial reinforcement, such as stone chip cushion, sand cushion and mixed lime soil backfill and compaction.
From the point of view of site construction, the foundation can be divided into natural foundation and artificial foundation. The foundation is the bearing stratum of rock and soil under pressure. Natural foundation is a natural soil layer that can meet the requirements of bearing all the loads of foundation in a natural state without reinforcement, which saves the project cost and does not need manual treatment. Natural foundation refers to the natural soil layer where the foundation can be directly placed without treating the foundation. It is divided into four categories: rock, gravel soil, sandy soil and cohesive soil. Artificial foundation: a foundation that has been artificially treated or improved. Natural foundation can be used when the soil layer has good geological conditions and strong bearing capacity; However, in areas with poor geological conditions, such as sloping land, sandy land or silt geology, or when the soil quality is good but the upper load is too large, in order to make the foundation have enough bearing capacity, artificial foundation should be used to strengthen the foundation.