Behavior of an Embankment on Column–Slab Improved Clay Deposit

Abstract

The performance of an embankment constructed on a cement deep mixing-formed column–slab system improved soft clay deposit was analyzed using field measurements and finite element simulation results. By back-fitting the measured surface settlement curve, it was interpreted that parts of the columns might have failed in compression, and the field mobilized compressive strength was lower than the designed value. Further, the numerical results indicate that some of the columns under the toe of the embankment failed by bending, but the current design method used in Japan does not check for this failure mechanism. In addition, for a soil–cement slab constructed on the ground surface, under a relatively high embankment load, tensile cracks will most likely form in the slab. Therefore, it is suggested that in design, the main function of the slab can be considered for reducing the differential settlement between columns and the surrounding soils; the strength of the slab may be ignored in stability analysis.