Gravelly soil (i.e. gravelly sands, sandy gravels, and uniform gravels) is generally recognized to have no or very low liquefaction potential. However, historically few case histories exist where observations of liquefied gravelly soils have been made, e.g. 1983 Borah Peak, Idaho earthquake (Youd et al. 1985), 1993 Hokkaido earthquake (Kokusho et al. 1995), 1995 Kobe earthquake (Soga, 1998) and 2013 Cook Strait earthquake (Van Dissen et al., 2015).
Since there are very few well-documented case histories of liquefied gravelly deposits in New Zealand, research in studying the liquefaction mechanism and developing proper analysing techniques for gravelly soils is necessary to characterise the hazard presented by these materials, so that engineers may effectively and economically minimize damage and loss caused by liquefaction of saturated gravelly soils. The results of this study will be valuable for characterising the impact and consequences of liquefaction on land and critical infrastructure during expected severe earthquakes, not only in the case of the Wellington reclamations but also for many critical infrastructure assets across New Zealand (dams, levees, bridge abutments/approaches, building foundations).
References
Youd, T.L. Harp E.L., Keefer, D.K., and Wilson, R.C. The Borah Peak, Idaho earthquake of October 28, 1983 – Liquefaction. Earthquake Spectra 1985; 2(4):71-89
Kokusho, T., Tanaka, Y., Kawai T., Kudo, K., Suzuki, K., Tohda, S. and Abe, S. Case study of rock debris avalanche gravel liquefied during 1993 Hokkaido-Nansei-Oki earthquake. Soils and Foundations, 1995, 35(3), 83-95.
Van Dissen, R., McSaveney, M., Townsend, D., Hancox, G., Little, T.A., Ries, W., Archibald, G., Dellow, G., Massey, C. and Misra, S. Landslides and liquefaction generated by the Cook Strait and Lake Grassmere Earthquakes: a reconnaissance report. NSSEE Bulletin, 2015, 46 (4), 196-200.
Soga, K. Soil liquefaction effects observed in the Kobe Earthquake of 1995. ICE Geotechnical Engineering, 131(1), 34-51.