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