Preliminary Study of the Damage Mechanisms of Hualien Harbor in the February 6, 2018 Hualien Earthquake

Preliminary Study of the Damage Mechanisms of Hualien Harbor in the February 6, 2018 Hualien Earthquake

After the Hualien earthquake on February 6, 2018, sand volcanoes of soil liquefaction and significant settlement were observed at gravel backfill backlands of Wharf 19-25 and the western breakwater, which significantly obstructed shipping work in Hualien Harbor. To better realize the liquefaction and settlement mechanisms of gravel backfill ground, a site with clear evidence of liquefaction and settlement was chosen at the backland of Wharf 25 for a series of tests, including a field test pit, standard penetration tests, shear wave velocity measurements, and laboratory tests. For comparison, a second site without obvious evidence of damage and close to Wharf 25 was selected for similar tests. Afterward, the testing results and seismic records for Hualien Harbor were collected to evaluate the liquefaction potential of the studied sites by using simplified methods based on the standard penetration test. Based on the field reconnaissance, testing results, analysis results, and existing completion drawings, the causes of the significant settlement of Wharf 25 are preliminarily deduced from the liquefaction at the shallow loose gravel and the densification effect of deeper reclaimed ripraps due to the strong ground vibration.