Dynamic Response of an Embankment during Stone-Column Piling

Stone-columns were used as part of Interstate 5 (I-5)/Interstate 805 (I-805) Highway Widening Project undertaken by the California Department of Transportation (Caltrans). During the stone-column construction, excessive slope movements were observed. Since no measurements were taken during construction, it was not known if the movements were caused by the vibration generated during the stone-column installation. A series of dynamic response analyses was conducted using the 2-D finite element computer program Plaxis to determine the probable causes of the observed slope movements by evaluating the possible correlations between the observed movements and the nearby stone-column installation activities. The overall study consisted of a test stone-column piling vibration measurement program and dynamic responses analyses. The piling measurement program was conducted to gather vibration data at various embankment points due to pilings. Two sets of dynamic response analysis were performed. The first set involved the embankment response analysis during the June 15, 2004, San Clemente Island earthquake. The results of the analysis were used to calibrate the dynamic soil parameters. The second set of analysis was carried out to assess the potential adverse impacts of the stone-column installation to the embankment stability. The second set of analysis included calibration of the dynamic soil parameters using the recorded vibrations from the test stone-column piling program. The results of the analyses indicate that the potential for excessive slope movements and failure due to stone-column piling exists.