Liquefaction-induced ground failure: a study of the Chi-Chi earthquake cases

Abstract

The 1999 Chi-Chi, Taiwan earthquake caused great destruction to buildings, bridges, and other facilities, and a death toll of more than 2400. Lessons should be learned from this event, which, albeit disastrous, represents a rare full-scale experimentation in geotechnical engineering and related fields. Of particular interest to geotechnical engineers is the phenomenon of soil liquefaction that caused significant damage to buildings, lifelines and harbor facilities. These liquefaction phenomena, in the forms of sand boils, lateral spreads, tilting and settlement of buildings, and ground settlement, were observed in the Chi-Chi event. Shortly after the earthquake, an extensive field investigation in the Yuanlin area, including in situ tests and laboratory tests, was conducted by Moh and Associates and other parties. These in situ and laboratory tests along with ground performance observations form the basis for the present study. In this paper, 24 cases of ground performance in the areas that suffered the most from liquefaction are studied. The ground performance in selected cases of the 24 cases is accounted for through a series of liquefaction analyses. The analysis of the potential of liquefaction and ground failure is performed using Cone Penetration Test (CPT) data. The results of the analyses show that the field observations of ground performance in the Yuanlin area in the Chi-Chi event can be accounted for satisfactorily using the evaluation procedure by Ishihara (Ishihara, K., 1985. Stability of natural deposits during earthquakes. Proc., 11th Int. Conf. on Soil Mechanics and Foundation Engineering, San Francisco, CA, vol. 1, pp. 321–376.).