Deformation response of shored MSE walls under surcharge loading in the centrifuge

ABSTRACT: In mountainous areas such as Colorado it is often necessary to extend the width of highway embankments to add traffic lanes. In such situations, a viable design alternative is to construct a mechanically stabilized earth (MSE) wall next to the existing, stable embankment. Because of the presence of the stable face of the embankment, shored mechanically stabilized earth (SMSE) walls can be constructed with shorter reinforcement lengths than conventional MSE walls. Although recent full-scale field studies of SMSE walls have verified the feasibility of these systems, an improved understanding of the deformation behavior of SMSE wall systems is needed. This paper describes a testing methodology to evaluate the deformation mechanisms of SMSE walls under surcharge loading in a geotechnical centrifuge. Scaling relationships were used to select the appropriate reinforcement material in centrifuge testing to represent typical full-scale SMSE walls. The methodology relies on a dense array of instrumentation to measure vertical settlement of a footing used to apply surcharge loads, lateral face displacements, and internal strains in the reinforced soil mass. The application of surcharge loads was observed to affect only the deformation response of the upper portion of the wall, and the maximum lateral face displacement occurred at the mid-height of the wall. Internal reinforcement strain distributions measured using tell-tales and digital image analyses indicate that the locations of the maximum tensile strain in the geosynthetic reinforcements in SMSE walls differ from those in conventional MSE walls. The observations indicate that sufficiently strong reinforcements should be used in SMSE walls to avoid internal rupture during surcharge loading.