Building Foundation Instability Induced by Tsunami Scour

Understanding the role of tsunami-induced scour in building foundation instability can allow for the proper design of buildings located in areas prone to tsunami events. The process of tsunami scour around building foundations reduces the bearing capacity of the soil to support loading, lateral resistance and loss of soil- foundation friction (i.e. piles). Scour can cause loss of material around a foundation, due to increased pore pressure within the soil and removal of the soil during the tsunami, resulting in reduced bearing capacity of the soil (Macabuag et al., 2018). During the 2004 Indian Ocean Tsunami and the 2011 Great East Japan Earthquake and Tsunami, three similar failure modes of building foundations were experienced, namely overturning, sliding and bearing (scour) failure (Macabuag et al., 2018). According to Wright (2015), shallow foundations such as strip, slab or pad are vulnerable to erosion of surrounding soil causing scour during a tsunami. The present paper discusses the application of the scour depth predictive model of Nicholas et al. (2016) and the development of a Relative Risk Index for future design of building foundations accounting for tsunamis