A nonlinear soil spring model considering ground stress and strain change during excavation

In practical designs, Winkler model is used to evaluate retaining wall behaviors during excavation. Soil spring coefficients have to be properly assigned in simulating retaining wall behaviors accurately. Soil spring properties are often represented by bilinear curves considering stiffness and ultimate ground reaction based on ground surveys. The stiffness of the soil spring is usually unchanged throughout the analysis. However, it is rational that the soil spring coefficients can be changed depending on ground stress and strain change during excavation. In this paper a simple nonlinear soil spring model is proposed considering ground stress and strain change during excavation. At an 11 m excavation site of Holocene clay ground in Tokyo-Bay area, retaining wall behaviors were observed. Analytical results by the proposed model showed excellent agreements with the observed results, which indicates that the proposed model, although it is simple, is promising for simulating retaining wall behaviors in a fairly reliable manner. In order to simulate retaining wall behaviors at different excavation stages, it is necessary to evaluate soil springs by using changes in soil stress and strain.