Accounting for Ground Motion Duration in Evaluating Liquefaction Triggering
The “simplified” liquefaction evaluation procedure is the most widely used approach for evaluating liquefaction triggering potential worldwide. In most variants of the simplified procedure, the influence of the ground motion duration on liquefaction triggering is accounted for using Magnitude Scaling Factors (MSF), designated as such because early studies correlated ground motion duration solely to earthquake magnitude, where ground motion duration was quantified in terms of number of equivalent cycles (neq). Recent studies have shown that neq, and hence MSF, are dependent on site-to-source distance, soil density, induced shear strain, and induced excess pore water pressure, as well as earthquake magnitude. However, in the study performed by the authors using a low-cycle implementation of the Palmgren-Miner fatigue theory, neq, and hence MSF, are shown to primarily be a function of peak ground acceleration (amax) at the surface of the soil profile and earthquake magnitude, and to be relatively independent of soil density, effective confining stress, etc. The dependence of neq and MSF on amax is consistent with the authors’ finding that neq correlates to the 5%-75% significant duration (D5-75%) of the ground motions and the findings by others that amax and D5-75% and are negatively correlated. The implications of the authors’ findings and proposed MSF on liquefaction triggering evaluations in New Zealand and worldwide are presented in this poster.
- Documents and Posters