Mechanical and Civil Engineering Seminar

Soil liquefaction has been responsible for considerable damage in earthquakes around the world.  Upon triggering, liquefaction leads to rapid, and often drastic, softening and weakening of a soil layer.  In sloping ground or level ground near slopes such as river banks or wharves, the softened and weakened soil can move laterally and cause damage to bridges and waterfront retaining structures.  Beneath buildings, these movements can damage pile foundations or cause significant settlement of shallow foundations.  The overwhelming majority of these deformations occur after liquefaction has been triggered and when the soil profile is in its softened state.  As a result, the stresses that drive the deformation result from the portion of the ground motion after triggering and the response that controls deformations is the response of the softened soils.  The presentation will illustrate these phenomena and describe a framework in which liquefaction-induced deformation are predicted on the basis of the ground motion intensity after triggering has occurred and using intensity measures that reflect the sensitivity of the softened soil profile to low-frequency components of the ground motion.