Probabilistic liquefaction risk assessment using the ground settlement for the Japan-wide area

抄録

In recent years, there have been research cases where information on liquefaction points during earthquakes has been developed and the occurrence rate and area rate of liquefaction can be evaluated. On the other hand, when predicting damage to structures due to liquefaction, it is necessary to evaluate not only the probability of occurrence and area rate, but also the amount of settlement due to liquefaction as a measure of the severity of liquefaction. The probability of occurrence is also important in considering structural countermeasures, and it is necessary to construct a probabilistic settlement hazard assessment. In this study, we used the amount of settlement as an index to evaluate the severity of liquefaction and developed a model to predict the amount of settlement due to liquefaction. Specifically, an estimation model that predicts the amount of settlement due to liquefaction based on geographical information such as seismic intensity and microtopography classification was developed using borehole data from liquefaction sites that occurred in Japan in recent years. Furthermore, using this model, we constructed a liquefaction hazard model for all of Japan with a mesh size of 250 m based on probabilistic seismic motion prediction maps and geographic information such as microtopography classification. Using the modeled hazard and building fragility corresponding to the amount of settlement, we evaluated liquefaction damage for an arbitrary earthquake scenario as a deterministic risk assessment. In addition, liquefaction damage with arbitrary probability was evaluated as a probabilistic risk assessment. The developed method makes it possible to assess liquefaction risk in a wide area throughout Japan based on the amount of settlement.