Characterization of Wall Deflection and Ground Settlement for Irregular-Shaped Excavations with Changes in Corner Configuration

Abstract

Excavation usually involves the three-dimensional behavior of the supporting wall and nearby ground as indicated by wall and ground movements. In this study, wall deflection and ground settlement behavior with excavation were investigated, focusing on the effect of excavation shape considering various excavation geometries and corner configurations. For this purpose, the three-dimensional finite-element analyses were performed for both regular and irregular excavation shapes. It was found that the wall deflection and surface settlement both increased with an increasing length-to-width ratio for the regular excavation shape. For the irregular excavation shape with a protruding corner, the corner-wall deflection and surface settlement were smaller than the longer-side wall and the regular excavation shape due to the corner stiffening effect. The location of the maximum wall deflection for the longer-side wall shifted to the longer-strut side when a corner existed. The depth of the maximum wall deflection for the longer-side wall was around 0.6 times of the excavation depth and deeper at the corner wall. The primary influence zone of ground settlement behind the wall was 1.0–1.5 times of excavation depth and larger at the corner side due to the combined wall deflection at the corner. In this study, the excavation behavior, including wall deflection and nearby ground settlement, for irregular excavation configurations was investigated. It was clearly observed that the wall deflection and ground settlement behaviors for regular and irregular excavation shapes were different. The main differences between the regular and the irregular excavation configurations were seen at the event of a protruding corner, given by the walls of W3 and W4 in the irregular excavation configuration. For the zone of the protruding corner, the depth of the maximum wall lateral deflection became deeper, and the influence range of surface settlement behind the wall was wider than that of the regular excavation configuration case at the same width and configuration. This behavior was attributed to the three-dimensional excavation effect that took place at the protruding corner. Wall deflection and surface settlement profiles were affected by both sides of the corner, and additional strains into the ground were caused. This indicates that adjacent structures near the protruding corner zone can be affected in a wider range and thus should be monitored more carefully. The results and characterized parameters obtained in this study can contribute to further enhancing excavation and wall design as well as to better establishing and networking the field monitoring system. This would be particularly important in urban areas where various types of structures and buildings are heavily located.