Influence and Mechanism of the Excavation Width on Excavation Deformations in Shanghai Soft Clay

Abstract

This study investigated the influence and mechanism of the excavation width on excavation deformations in Shanghai soft clay. Based on three excavations that had different final excavation depths, dissimilar retaining structures and diverse geological conditions, 40 sets of two-dimensional numerical models with different excavation widths were employed to analyze the deformation rules affected by the excavation width. Moreover, a series of simplified models with different excavation widths were employed to analyze the effect of the excavation width on excavation deformations. The results show that under the same excavation depth, both the horizontal displacements of the retaining walls and ground surface settlements increase as the excavation width increases, but the increasing rate gradually decreases. Factors such as the unloading influence depth, the overlap degree of the passive zones, the stress state of the basal soils and the development of the relative shear stress have a significant influence on excavation deformations. With increasing excavation width, the unloading influence depth gradually deepens, the overlap area of the passive zones gradually decreases, the direction of the rotation of the major principal stress gradually reduces and the relative shear stress of the distant and deep soils gradually expands. Therefore, the constraint ability of the passive zones on excavation deformation gradually reduces and excavation deformations gradually increase.

Keywords

• deep excavation
• excavation geometry
• deflection
• settlement
• soft clay