Replacement method is also called soil replacement method. The so-called soil replacement method refers to clearing the soft soil in the subgrade, backfilling the stable soil and stone, and compacting or tamping. In highway construction, excavation is generally used to replace natural gravel, that is, within a certain range, the muddy soft soil that affects the stability of subgrade is excavated by excavator and replaced with natural gravel. Digging and replacement depth is less than 2m, layered filling, layered compaction, layered detection of compaction degree for construction. Thereby changing the bearing characteristics of the foundation and improving the deformation resistance and stability. In the process of replacement, the particle size, content and gradation of stones in natural gravel should also be fully considered, and it is best to do experimental tests to avoid settlement caused by compaction.
It is difficult to clearly define the boundary between shallow treatment and deep treatment. Generally speaking, it can be considered that the scope of shallow foundation treatment is roughly within 5 meters below the ground. The adoption of shallow artificial foundation depends not only on the size of building load, but also on the physical and mechanical properties of foundation soil to a greater extent. Compared with deep foundation treatment, shallow foundation treatment generally adopts simpler technology and construction equipment and consumes less materials.