Abstract: The earth pressure theory by Rankine and the formula for calculating subsidiary stress by Boussinesq were employed to study the interaction between earth berm and retaining structure for cantilever retaining structure. On one hand, the earth berm in a pit can strengthen horizontal resisting force of the soil body in the passive zone owing to its gravity. On the other hand, it can reinforce the stability of the retaining structure due to the horizontal resisting force of itself. Considering the two points aforementioned, a method is constructed to determine embedment depth of retaining structures. And more, a pit excavation is computed by the proposed method for further investigations. The study shows that reinforcement of the earth berm on retaining structure is remarkable because of the large moment arm even the magnitude of the horizontal resisting force is not very great. Therefore, the needed embedment length of the retaining structure in the pit excavation having earth berm can be distinctly cut. It can be concluded that the earth berm method should be recommended in suitable situations for its better economy, higher efficiency and lower pollution.

Key words: pit excavation, earth berm, cantilever, embedment depth, resisting force