Centrifuge Modeling of Downward Soil Arching below Excavation Base in Dry Sand

Abstract

Excavation-induced soil arching is a key factor influencing the responses of the ground and underlying structures. This soil arching below an excavation base is defined as downward soil arching in comparison with that above a trapdoor or tunnel, featured with the downward developing direction. To recognize and assess the downward soil arching, two centrifuge tests in the plane-strain condition were conducted in the dense and loose sand. Variations of Earth pressure, basal heave, and shear wave velocity below the excavation base were observed, and the influence of the relative density was also investigated. The test results indicated the existence of differential deformation and stress transfer below the excavation base, and the downward soil arching is confirmed. The contributions of the downward soil arching to the restriction of the excavation-induced stress release and the ground response were found. Further, the boundary of the loosened zone and the width of the arch foot were determined in the dense and loose sand, respectively. In addition, the arched-type basal heave and stress-related shear wave velocity were observed. The significant ground heave and reduction of the shear wave velocity were found within the loosened zone.