Methods for Evaluating Residual Post-Liquefaction Ground Settlement and Horizontal Displacement

Abstract

During the 1995 Hyogoken-Nambu earthquake, large vertical residual ground settlements and horizontal displacements extensively occurred in liquefied soils behind caisson-type quay walls where lateral movements of the walls towards sea were led by strong seismic shaking. Case studies further show that both significant vertical residual ground settlements and horizontal displacements were also induced by this earthquake in liquefied level sandy ground with a sufficiently large lateral extent where no significant initial shear stresses were present. The mechanism regarding the occurrence of the above phenomena is revealed through new post-liquefaction stress-strain constitutive analysis. Consequently, the residual post-liquefaction ground settlement and horizontal displacement are found to be interdependent of each other, so that neither cannot be determined separately in principle. A new methodology with pragmatic charts is developed for concurrently evaluating the residual post-liquefaction ground settlement and horizontal displacement in liquefiable ground. The prediction results using the proposed method agree with actual observations during the 1995 Hyogoken-Nambu earthquake.

Recent Advances in Seismic Soil Liquefaction Engineering

“…It should be noted that higher values of maximum likelihood and lower values of standard deviation are also indicators of a better model. As the values of the calibration coefficient, θ, presented in Table 19.1 implies, existing methods of Shamoto et al (1998), Tokimatsu and Seed (1984), and the proposed methodology under-predict the actual settlements by a factor of 1.91, 1.45 and 1.15, respectively. Similarly, Wu and Seed (2004), and Ishihara and Yoshimine (1992) over-predict settlements and need to be corrected by a factor of 0.98 and 0.90.…”

“…The proposed method was calibrated via 49 well-documented cyclically-induced ground settlement case histories from seven different earthquakes. Within the confines of that study, performance of the widely used methods of Tokimatsu and Seed (1984), Ishihara and Yoshimine (1992), Shamoto et al (1998), Wu and Seed (2004) were comparatively evaluated. It was concluded that the proposed methodology, details of which will be given next, produced more accurate and precise settlement estimations compared to all other efforts.…”

“…Similarly, based on the results of cyclic simple shear tests, Ishihara and Yoshimine (1992) proposed cyclically-induced maximum shear and post-cyclic volumetric strain correlations, where normalized demand term was chosen as factor of safety against liquefaction, and capacity term was defined as relative density (D R ), or cone tip resistance (q c ), or SPT blow count (N 1,72 ). Based on the results of cyclic torsional shear tests, Shamoto et al (1998) recommended a semi-empirical constitutive model, as well as chart solutions, for the estimation of post-cyclic residual shear and volumetric strains. Recently, Wu et al (2003) proposed cyclically-induced limiting shear and post-cyclic volumetric strain correlations based on the results of cyclic simple shear tests.…”

“…Lee and Albeisa (1974), Tokimatsu and Seed (1984), Ishihara and Yoshimine (1992), Shamoto et al (1998), Zhang et al (2002), Wu and Seed (2004), Tsukamato et al (2004), etc.). Due to difficulties in the determination of input model parameters necessary for numerical simulations, semi-empirical models continue to establish the state of practice for the assessment of cyclicallyinduced reconsolidation (volumetric) settlements.…”

“…For comparison purposes, each case history site (presented in detail in Bilge and Cetin 2007) was analyzed by using the methods of Tokimatsu and Seed (1984), Ishihara and Yoshimine (1992), Shamoto et al (1998), Wu and Seed (2004) and finally the proposed method. The performance of the model predictions, expressed by Pearson product moment correlation coefficient, R 2 , is summarized in Table 19.1.…”