Simplified procedures for assessing soil liquefaction during earthquakes

Abstract

Simplified methods to evaluate the effects of saturated sandy soil liquefaction are needed for reasonable earthquake resistant design of structures considering the surrounding soil liquefaction. The authors, Iwasaki et al.,¹ proposed two simplified methods with use of a liquefaction resistance factor F_L and a liquefaction potential index I_L to evaluate the liquefaction potential of saturated sandy soils. Based on the proposed methods, the liquefaction potential can be estimated simply by using the fundamental properties of soils, i.e. N-values of the standard penetration test, unit weights, mean article diameters, and maximum acceleration at ground surface. In this paper, the two simplified methods are firstly introduced, and to prove the effectiveness of the proposed methods the values of both F_L and I_L at 64 liquefied sites and 23 non-liquefied sites during past six earthquakes are calculated according to the simplified methods. Also shaking table tests on soil liquefaction are carried out for the saturated sandy model ground. Furthermore, several application methods using the factor F_L, the excessive pore water pressure induced in the saturated sandy soils and the effects of soil liquefaction on the resistance properties of grounds surrounding structures are described.