Lateral Spreading and Stability of Embankments Supported on Fractured Unreinforced High-Modulus Columns

Abstract

Construction of column-supported embankments (CSEs) with unreinforced high-modulus elements is now common practice to accelerate fill placement. These brittle columns are susceptible to column fracturing and CSE designs often limit the degree of lateral spreading such that tensile rupture will not occur, which stems from salient concerns that fracturing may trigger uncontrolled lateral spreading and/or the cessation of intended vertical load transfer. However, tensile rupture is unlikely to coincide with full mobilization of available passive resistance at the toe. Thus, it is disputed in industry whether some degree of column fracturing is tolerable. The objective of this study is to elucidate the influence of column fracturing on lateral spreading and stability of CSEs. A collective examination of available performance data is accompanied by a parametric 3D finite element study of hypothetical embankments, which considers the cessation of column bending resistance due to tensile rupture at discrete crack locations. A factor of safety, which reflects development of a passive failure wedge at the embankment toe, is used as a proxy for lateral stability. Factors of safety are linked to the magnitude of lateral spreading to address whether adequate confinement can be provided by foundation soils when fracturing occurs in unreinforced high-modulus columns that support embankments.