Abstract:In the soft soil areas, especially adjacent to water, the water-washing method can be used for the excavation of extra-large deep foundation pits. The technological principle, characteristics, scheme and technological process of water washing method, and the equipment and personnel allocation are introduced. Take a single foundation pit in the subarea of extra-large deep foundation pit as an example, the efficiencies of the water washing method and traditional mechanical excavation are analyzed, and the economic cost of these methods are calculated in order to summarize the possible technological problems and to propose the relevant solutions. The comparison and analysis results show that the water-washing method is very suitable for the excavation of extra-large foundation pits adjacent to water, and can be used in the excavation of large foundation pits in the many large airport terminals.