Effective Stress Analysis of Quay Walls During the 2011 East Japan Earthquake

Abstract

Numerous quay walls were damaged due to ground motions and subsequent tsunami during the 2011 Great East Japan Earthquake off the Pacific Coast of Tohoku, especially in the area south of the epicenter. Although it is assumed that liquefaction due to the ground motions occurring before the tsunami magnifies the tsunami damage, the severity of liquefaction and related damage to the quay walls before the tsunami is unknown. Various numerical simulations are performed for understanding the damage mechanisms caused by the ground motions using a strain space multiple mechanism model, called the cocktail glass model, as a constitutive model for soils. If a sheet pile type quay wall can retain structural stability and the excess pore water pressure dissipates before the arrival of a tsunami, the quay wall will not collapse due to a tsunami attack. However, a caisson-type quay wall, even if the quay wall retains its structural stability, may deform due to rubble foundation scouring caused by a tsunami attack. In addition, the cocktail glass model, which can consider the effect of pore water migration and dissipation, is applicable to evaluate the seismic performance such as deformation of quay walls against strong, long-duration ground motions.