An innovative method to evaluate degree of compaction of river embankments using CPT

The paper illustrates an innovative method to evaluate the degree of compaction of both existing and new river embankments after their completion. A tip resistance target - profile is inferred from laboratory tests in a mini calibration chamber (CC) using a mini CPT. The “laboratory” tip re-sistance (qcLAB) is expressed as a function of the expected density and of the vertical – horizontal stress components. Such a dependence of qcLAB is obtained carrying out a number of repeated tests in the CC at given density and different consolidation stresses. In situ stresses are inferred by combining DMT results and an estimate of the vertical stress component. A comparison between the q cLAB profile, from CC testing, and the qc , as inferred from in situ CPT, gives the possibility of assessing the density of existing embankments, while, for new embankments, the method defines the expected in situ qc for a given target density. This method has been successfully used in some case histories (already published data). The paper, after the description of the method, focuses on the effects of stresses on the tip resistance in the case of dry sand and partially saturated fine soil. Eventually, a correlation is attempted between the tip resistance and the dynamic modulus (Ed) as inferred from LFWD. Indeed LFWD could be a useful and ex- peditious tool for controlling the degree of compaction during the construction stage.