In order to evaluate the densification of each layer in the layer compaction, sand cone and plate loading test are frequently used in Korea. As these evaluation techniques are intrusive and test results depend on equipment and testing personel, development of reliable density evaluation techinque is needed.
The Spectral-Analysis-of-Surface-Wave(SASW) method is an nonintrusive and spatial test to representing average soil properties to determine shear wave velocity (Vs) of soil deposits and shear stiffness profile using the dispersive characteristics of surface waves. SASW method has a great potential for rapid and reliable determinaton of Vs compared to other in-situ tests. However, this method requires an inversion process to determine Vs profile which needs skillful engineers.
In the layer compaction, if each layer of about 0.3m can be assumed as homogeneous and shows no dispersive characteristics, there is a possibility to get a representative shear wave velocity in the SASW test without inversion.
In this study, SASW test was used to determine the shear wave velocity of compacted layer, and FF-RC test was adopted to determine the correlation between the normalized shear wave velocity and density of the site which is almost independent of confinement. Testing and data reduction procedures of both test were discussed, and a procedure for evaluation density was proposed by effectively combining in situ shear wave velocity determined by SASW tests with the correlation between normalized shear wave velocity and density determined by FF-RC tests. Finally, the feasibility of the proposed method was verified by performing field studies at Hoengsung Road Construction Site. Field densities determined by the proposed method matched well with those determined by sand cone tests.
