Underground Singapore 2011

Page 97

Underground Singapore 2011

Figure 5 Measured maximum lateral wall movement vs Depth of excavation

Figure 6 Measured maximum ground settlement vs depth of excavation

Figures 5 and 6 are measured maximum wall and soil movements plotted against He for braced excavation. Both figures have disclosed a general pattern of wall movement and adjacent ground settlement, which can be useful as design tools to estimate maximum wall and soil movements. In Figure 5, it can be seen that the data scatter between hm/He of 0.1% and 0.5%, which is similar to those presented by Ou et al. (1993). In Figure 6, the data scatter between vm/He of 0.05% and 0.4%. Observations of movements of soil adjacent to excavation provide the best way to define ground settlement likely to occur in the field. However, it is well known that field measurements can involve significant movement components caused by activities such as dewatering and construction loading. Therefore, it is logical to treat these components separately and to focus on the soil movements caused by excavations. In this study, each set of field measurements involving inclinometers and corresponding settlement markers was screened to preclude movements not primarily related to the excavation works.

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