Evaluation of Tsunami Induced Scour on Shallow Foundations using Empirical Formula: Case Study of Patong Beach

Abstract

Although tsunamis are infrequent, they can cause severe damage to human lives, property, ecosystems, and the economy. While coastal structures can be designed to withstand tsunami-induced forces, the scour around shallow foundations due to tsunami flows increases the foundations’ exposure to hydrodynamic forces. This phenomenon reduces foundation stability and may lead to structural overturning failure. Some residential structures in coastal areas of Thailand use shallow foundations, which are vulnerable to tsunami-induced scour. This study aims to investigate the tsunami-induced scour depth at Patong Beach, Phuket Province, Thailand. The tsunami inundation depth and flow velocity are evaluated using the Energy Grade Line method. Scour depths are estimated using empirical equations proposed by Sumer et al. Subsequently, tsunami-induced forces acting on foundations are evaluated using the drag equation. The results indicate maximum scour depths of 1.3 times the diameter for circular piers and 2 times the width for square piers. Additional hydrodynamic forces after scour range from 0.75–2.0 kN for circular piers and 2.0–15 kN for square piers. These forces should be incorporated into shallow foundation stability analyses.