Analysis of a Column-Supported Test Embankment at the I-95/Route 1 Interchange

Deep mixing stabilization supports new embankments over deposits of soft organic silts and clays at the I-95/US Route 1 interchange reconstruction in Alexandria, Virginia. During design, an instrumented test embankment was constructed on dry mix columns to assess performance of this technology at the interchange site. Numerical modeling disclosed that the most significant material properties affecting stress concentrations in the soil above the columns are the strength and stiffness of the columns, while the shear modulus of the untreated clay is most important for lateral deformations at the end of construction. As the column strength and stiffness increase, the stress concentration ratio increases. As the soil shear modulus increases, the lateral deflections decrease. The values of stress concentration ratio from the calibrated numerical model are 4.2 and 2.1 for area replacement ratios of 6.4% and 17.9%, respectively.