Validation of the Energy-Based Method for Evaluating Soil Liquefaction in Centrifuge

Extensive research has been conducted at Case Western Reserve University to introduce and evaluate the energy concept in defining the liquefaction potential of soils when subjected to dynamic loads. Generalized relationships were obtained by performing regression analyses between the energy per unit volume at the onset of liquefaction and liquefaction affecting parameters. This study deals with evaluating and examining the suitability of these relationships using centrifuge modeling. Centrifuge liquefaction testing of several soils with different grain-size characteristics made it possible to evaluate the validity of the energy method in determining the liquefaction potential of a soil deposit. Dynamic centrifuge tests were conducted on scaled pore fluid-saturated models, prepared in a laminar box, representing a prototype thickness of 7.6 m. A simplified procedure for estimating the energy per unit volume from the recorded horizontal accelerations and the lateral displacements at different depths is presented. The total energy at the onset of liquefaction is obtained from the stress-strain time histories from centrifuge testing results and compared with the same energy calculated from regression equations developed through torsional series tests. A rational procedure to decide whether or not liquefaction of a soil deposit is imminent can be formulated by comparing the calculated unit energy from the time series record of a design earthquake with the resistance to liquefaction in terms of energy, based on in situ soil properties