Behavior of an embankment on New York varved clay

Abstract

The foundation soils for an embankment in New York State constructed on preconsolidated varved clay were instrumented to determine pore pressures and settlements during and after construction. Four embankment cross sections, three of which had sand drains, are analyzed in this paper. Predictions of the in situ undrained pore pressures, initial settlements and final consolidation settlements are presented and compared with the results of field measurements. Undrained pore pressures and initial settlements are predicted using the finite element program FEECON for plane strain embankment conditions and elastic theory for three-dimensional embankment conditions. Final consolidation settlements are predicted using a modification of the Skempton–Bjerrum approach. At cross sections with sand drains, predicted undrained pore pressures are adjusted to account for the effect of the sand drains. In addition, vertical and horizontal coefficients of consolidation are determined from the field measurements and compared with laboratory values of vertical coefficients of consolidation. The results of the investigation indicate that the proposed prediction techniques yield reasonable predictions of undrained pore pressure and initial settlement. Additional case studies are required in order to evaluate the predictive methods for the rate and amount of consolidation settlement.