No abstract

Over the past two decades, extreme flood events generated by tsunamis or hurricanes have caused massive damage to nearshore infrastructures and coastal communities. Utility pipelines are part of such infrastructure and need to be protected against potential extreme hydrodynamic loading. Therefore, to address the uncertainties and parameters involved in extreme hydrodynamic loading on pipelines, a comprehensive experimental program was performed using an experimental facility which is capable of generating significant hydraulic forcing, such as dam-break waves. The study presented herein examines the dam-break flow characteristics and influence of the presence of pipelines on flow conditions. To simulate conditions of coastal flooding under tsunami-induced inundation, experiments were performed on both dry and wet bed conditions to assess the influence of different impoundment depths and still water levels on the hydrodynamic features.

Adequate design of pipelines used for oil, gas, water, and wastewater transmission is essential not only for their proper operation but particularly to avoid failure and the possible extreme consequences. This is even more drastic in nearshore environments, where pipelines are potentially exposed to extreme hydrodynamic events, such as tsunami- or storm-surge-induced inundation. The American Society of Civil Engineers (ASCE), in its ASCE7 Chapter 6 on Tsunami Loads and Effects which is the new standard for tsunami impacts and loading, specifically stresses the need to study loads on pipelines located in tsunami-prone areas. To address this issue, this study is the first of its kind to investigate loading on pipelines due to tsunami-like bores. A comprehensive program of physical model experiments was conducted in the Dam-Break Hydraulic Flume at the University of Ottawa, Canada. The tests simulated on-land tsunami flow inundation propagating over a coastal plain. This allowed to record and investigate the hydrodynamic forces exerted on the pipe due to the tsunami-like, dam-break waves. Different pipe configurations, as well as various flow conditions, were tested to investigate their influence on exerted forces and moments. The goal of this study was to propose, based on the results of this study, resistance and lift coefficients which could be used for the design of pipelines located in tsunami-prone areas. The values of the resistance and lift coefficients investigated were found to be in the range of 1 < CR<3.5 and 0.5 ≤ CL<3, respectively. To that end, the study provides an upper envelope of resistance and lift coefficients over a wide range of Froude numbers for design purposes.

No abstract

The complex hydrodynamics during a tsunami event can significantly affect the structural integrity of buildings. The resulting hydrodynamic forces are influenced by various fluid parameters such as the fluid density, flow velocity and depth, as well as by the structure’s geometry. Hydrodynamic forces induced by tsunami pressures and velocities are particularly important, as they occur usually around a coastal defence structure or a building and as a result, they affect the structural integrity of the structure (Chinnarasri et al, 2013). The 2011 Japan post-tsunami field survey of Chock et al. (2013) indicated that lateral pressures, uplift pressures and surge flow from the tsunami produced hydrodynamic forces responsible for the destruction of many structures along the Tohoku coastline. The associated hydrodynamic parameters of a tsunami such as pressures and velocities also influence the tsunami-induced scour around buildings. Nicholas et al. (2016) stated that the tsunami-induced hydrodynamic velocity was a crucial factor in producing soil-scour around building structures.