Semi-empirical procedures for evaluating liquefaction potential during earthquakes

Energy-based evaluation of liquefaction potential under non-uniform cyclic loading

“…Seed and Idriss 1971;Ishihara and Yasuda 1975;Idriss and Boulanger 2006), a singular peak loading cycle with twice the amplitude of the remaining uniform loading cycles was considered. The location of the higher amplitude peak within the overall loading pattern, defined by the specific value of mean effective stress at which the loading regime is changed, p'p, was varied in each test, in order to assess its influence on the liquefaction resistance of sand.…”

“…According to Liang et al (1995), when compared to alternative stress-based (e.g. Seed and Idriss 1971;Seed et al 1975;Idriss and Boulanger 2006) and strain-based (e.g. Dobry et al 1982) approaches, energy-based methods have the strong advantage of accounting for both induced shear stress and strain, thus avoiding the need to decompose the irregular shear stress (or strain) time histories to find an equivalent uniform loading.…”

“…Moreover, conventional undrained cyclic triaxial tests using uniform loading were also carried out in order to assess whether stress-based methods can adequately deal with the irregularity of loading. The stress oscillations imposed in these conventional tests were chosen to be equivalent to those imposed in the non-uniform triaxial tests in accordance with the methodology proposed by Seed and Idriss (1971) and Idriss and Boulanger (2006). Based on the obtained results, it is discussed whether or not conventional laboratory tests using uniform loading can be reliably used for the evaluation of liquefaction resistance.…”

Analysis on Settlement of Soil Deposits Following Liquefaction During Earthquakes

“…The northern half of Kobe Port Island was reclaimed with weathered granite brought from the Rokko mountains, located behind Kobe city, at a seabed of 10 to 15 metres deep from 1966 to 1980. The reclaimed deposits settled 30 to 60 cm following extensive soil liquefaction, Yasuda et al, 1996;Idriss and Boulanger, 2008). Figure 7 shows the settlements observed at the bridge piers for the elevated new transportation railway at Kobe Port Island.…”

“…1, it is also necessary to determine the factor of safety Fl. When the liquefaction resistance of soils can be estimated from laboratory triaxial tests or other empirical formulae, the value of Fl can be evaluated by employing the usual procedures, (Ishihara, 1996;Idriss and Boulanger, 2008; and others). The problems associated with the use of Fl in Fig.…”