Method and Application of Liquefaction Probabilistic Risk Assessment

Method and Application of Liquefaction Probabilistic Risk Assessment

Liquefaction is a phenomenon in which cohesionless saturated soils lose their integrity by earthquake or other rapid loading. The damages to the structure that are built on top of or buried into the liquefied soil could be significant as liquefaction causes excessive ground surface settlement, bearing capacity failure of the foundation, lateral movement of slopes, or floatation of buried structures. These structures may sink, fall over, or float, and therefore complete loss of structural functionality and significant casualties may occur. As a result, evaluation of liquefaction potential is crucial. The available methods for computing the liquefaction potential are mostly deterministic which provide a binary result (i.e. they only describe either the liquefaction will or will not occur). Some methods may also provide a safety factor. This is not satisfactory for risk-based designs and for the decision makers as they want to know the probability of the occurrence of liquefaction in various scenarios. In this article, a noble framework is proposed which uses the Liao’s regression model besides the fragility safety factor method to evaluate the probability of liquefaction at a site. This method will be used to derive the seismic liquefaction fragility curve of a soil site which a nuclear power plant will be built on top. This fragility curve will be used in the seismic probabilistic risk assessment (PRA) of the plant.

Liquefaction is a phenomenon in which cohesionless saturated soils lose their integrity by earthquake or other rapid loading. The damages to the structure that are built on top of or buried into the liquefied soil could be significant as liquefaction causes excessive ground surface settlement, bearing capacity failure of the foundation, lateral movement of slopes, or floatation of buried structures. These structures may sink, fall over, or float, and therefore complete loss of structural functionality and significant casualties may occur. As a result, evaluation of liquefaction potential is crucial. The available methods for computing the liquefaction potential are mostly deterministic which provide a binary result (i.e. they only describe either the liquefaction will or will not occur). Some methods may also provide a safety factor. This is not satisfactory for risk-based designs and for the decision makers as they want to know the probability of the occurrence of liquefaction in various scenarios. In this article, a noble framework is proposed which uses the Liao’s regression model besides the fragility safety factor method to evaluate the probability of liquefaction at a site. This method will be used to derive the seismic liquefaction fragility curve of a soil site which a nuclear power plant will be built on top. This fragility curve will be used in the seismic probabilistic risk assessment (PRA) of the plant.