APPLICATION OF GROUND SPRING MODEL IN EXCAVATION SUPPORTED BY DEEP CEMENT MIXING

Abstract

An application of Deep Cement Mixing (DCM) as a retention system in deep excavationbecomes gradually popular in very dense population areas because of less noise and environmental impact ofthe construction process than other systems. In addition, this new kind of retention system has various formsof utilization, which depend on the designer’s experience and considerations. For better understanding of thissystem, full scaled test, down scaled physical model test, and numerical analysis are required to tackle theinterested problem. To effectively discuss the behaviors observed from the full-scale numerical analysis andphysical model test, the scaling factor must be seriously considered. However, it is difficult to scale down theproperties of soft clay in the physical model test. Therefore, the soil and its lateral pressure transferred to thewall are modeled as a series of springs and lateral forces in the model, respectively. To ensure the effectivenessof this modeling, preliminary evaluation is necessary. In this study, a 2D plane strain Finite Element model ofan excavation with the DCM retaining wall had been validated with field monitoring data, then the 2D modelwas compared to a 3D Finite Element model with a series of ground springs to take the lateral stiffness of thein-situ soil behind the wall into consideration. The results of this numerical investigation reveal that the groundspring model has sufficient accuracy to represent the lateral soil-structure interaction.