Abstract: The feasibility of applying soil-nailed support techniques to soft clay foundation pit of 6.0 -7.0m depth is analyzed based on discussing the features of soft clay ground and the support of foundation pit actualities. At the project of Zhenhai Refining & Chemical Company the soil-nailed wall is adopted successfully in 6.0m-depth foundation pit in the super soft soil. It is the first case of soil-nailed wall applied to soft foundation pit in Ningbo urban area; and it creates a precedent for this kind of technique. Because of the particularity of Ningbo soft foundation the possible problems should be predicted and prevented from during the construction. The experience and lesson about the soil-nailed wall design and construction are described in detail and the appropriate support structure type fitting to Ningbo soft soil foundation pit is advanced. Soil-nailed support techniques shall be widely used in Ningbo urban area due to its economy and rationality.

Key words: soil-nailed wall, super-soft foundation, support of foundation pit