Investigation of the effect of underwater explosion on damage of offshore platform piles

In recent years, due to a large number of accidental incidents and terrorist bombings, it has become very important to predict the vulnerability of marine structures. The underwater explosion is one of the destructive phenomena of marine structures, and understanding the mechanism of this type of explosion can be very important to study its effects on marine structures performance. The purpose of this paper is to investigate the failure of concrete piles due to underwater explosion and parametric study of the effect of variation of blast depth and pile diameter on the dynamic response of concrete piles under underwater explosion using sensitivity analysis and its application in selec the optimal value of the parameter. Ansys Workbench software is used for modeling and analysis and explicit method is used to solve the dynamic equations. The explosive is considered to be TNT with 203 Kg mass with a standoff distance of 3 meters from one of the piles and the equivalent weight of the platform was applied to the pile. The results show a significant effect of the underwater explosion on dynamic response. Based on these results, it can be concluded that the explosion at medium depths has the most damage compared to the explosion near the water surface or bed. Also, the results illustrate the trend of overall damage decreasing with increasing of pile diameter.