Limits on Coastal Scour Depths due to Tsunami

Tonkin, Susan P.; Francis, Mathew; Bricker, Jeremy D.

doi:10.1061/9780784413234.086

Cited by 18 publications

(13 citation statements)

References 2 publications

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“…Equation 9 provides a simple empirical prediction based on observations of local scour depths and estimated flow depths for different sediment types in the aftermath of the 2011 Tohoku tsunami (Tonkin et al, 2014). In ASCE 7-16 the extent (length) of the scour hole around corner foundations l scour (see Figure 2) is dependent on the soil type and is calculated as follows:…”

Section: Index For Structural Stability Under Scour Rri Scourmentioning

confidence: 99%

A New Relative Risk Index for Hospitals Exposed to Tsunami

et al. 2021

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The failure of hospitals in recent tsunami have caused extensive social and economic losses. A simple but quantitative approach is required to assess the resilience of healthcare systems to tsunami, which relates not only to hospital building integrity, but also to maintaining hospital functionality. This paper proposes a new tsunami relative risk index (TRRI) that quantifies the impact of tsunami on critical units, (e.g. Intensive Care Unit, Maternity Ward, etc) in individual hospitals, as well as the impact on service provision across a network of hospitals. A survey form is specifically developed for collecting of field data on hospitals for the TRRI evaluation. In its current form TRRI is designed for hospital buildings of reinforced concrete construction, as these are the building types most commonly used worldwide for housing critical units. The TRRI is demonstrated through an application to three hospitals located along the southern coast of Sri Lanka. The TRRI is evaluated for three potential tsunami inundation events and is shown to be able to identify issues with both the building and functional aspects of hospital critical units. Three “what-if” intervention scenarios are presented and their effect on the TRRI is assessed. Through this exercise, it is shown that the TRRI can be used by decision makers to simply explore the effectiveness of individual and combined interventions in improving the tsunami resilience of healthcare provision across the hospital system.

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Section: Index For Structural Stability Under Scour Rri Scourmentioning

confidence: 99%

A New Relative Risk Index for Hospitals Exposed to Tsunami

et al. 2021

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“…(a) general erosion marking a loss of land surface over large spatial extents (Dalrymple and Kriebel 2005, Shuto and Fujima 2009, Kato et al 2012, Yeh et al 2013, Fraser et al 2013), (b) sustained flow scour near corners and sides around free-standing structures, with scour depth ranging from 0.5 -4.0 m being reported by post-tsunami field surveys (Bricker et al 2012, Tonkin et al 2013), (c) channelized scours in between gaps of larger buildings, as reported by Yeh et al (2013) in the city of Onagawa, Japan during the 2011 Tohoku Earthquake Tsunami, and (d) overtopping scour behind coastal line defenses such as sea walls, where overtopping jets plunging over the structures cause excessive soil erosion (Yeh et al 2004, Kato et al 2012, Mikami et al 2014, Jayaratne et al 2016. All forms of scouring listed above may, when the extreme flow event is persistent and exposes the soil to shear stresses larger than the critical shear stress, result in scouring that could eventually damage structures; only recently, guidelines and standards have started to address this important issue.…”

Section: General Erosion 221mentioning

confidence: 99%

“…Whereas seismic liquefaction occurs during the high frequency shaking of the ground, pore pressure softening is the result of a long period inundation loading followed by a rapid drawdown, leading to an abrupt release of hydrostatic pressure. Tonkin et al (2003), Yeh et al (2004) and Tonkin et al (2013) derived an equation to describe the depth d s of tsunami-induced liquefaction based on the one-dimensional consolidation model with an excess pore pressure field from Terzaghi (1925). These studies built upon a scour enhancement parameter, which defines the critical fraction of the buoyant weight of soil supported by pore pressure.…”

Section: Pore Pressure Softening 222mentioning

confidence: 99%

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Engineering Lessons from September 28, 2018 Indonesian Tsunami: Scouring Mechanisms and Effects on Infrastructure

Krautwald

Stolle

Robertson

et al. 2021

J. Waterway, Port, Coastal, Ocean Eng.

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The 28th of September 2018 earthquake and tsunami north of Palu, Indonesia, attracted widespread interest from the scientific community due to the unusually large tsunami which occurred after a strike slip earthquake with a relatively small moment magnitude (M W = 7.5). To understand the structural performance of buildings and infrastructure under hydrodynamic loads and its associated effects the authors conducted field surveys of Palu City. Light wooden frame constructions and masonry infill walls were common in the area, some of which were severely damaged by the earthquake and tsunami. Reinforced concrete structures remained predominantly intact, though suffered soil-related issues such as scour around rigid building members. Local structural failures caused by the loss of supporting soil were also observed during the field survey, resulting in an overall reduction in the stability of the inspected structures. Based on the observations made, knowledge gaps and research needs concerning coastal and structural scouring are discussed. These are tied into the latest community research activities and put in the context of the published tsunami design standard in Chapter 6 of ASCE 7-16 (2017).

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“…In the case of tsunami induced scour, the literature is more limited and eld investigations of tsunami-induced scour are the primary source of scour data. Post-tsunami investigations of scour include Wilson et al (2012) in harbours, Tonkin et al (2013) at roads and structures, and Bricker et al (2012) at coastal defences. Such retrospective investigations are few in number, geographically localised and infer only post-tsunami scour depths, extents and volumes; they are unable to provide systematic elucidation of the processes and mechanisms of scour evolution.…”

Section: Introductionmentioning

confidence: 99%

Experimental observations of tsunami induced scour at onshore structures

McGovern

Todd

Rossetto

et al. 2019

Coastal Engineering

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Tsunami inundation of the coastal environment can induce scour at structure foundations leading to failure. A series of experiments are made using a unique Pneumatic Long Wave Generator to generate tsunami wave periods of 25-147 s equating to 3-17.3 mins at 1:50 Froude scale. The waves propagate over a sloping bathymetry and impinge upon a square structure founded onshore in a at sediment bed. Flow velocity, height and scour are recorded as a function of time during tsunami inundation. The rate of scour is observed to be time dependent. Equilibrium, which is not attained, is argued to be an inappropriate measure for time-dependent transient ows such as tsunami in which the ow velocity, depth and direction are variable. The maximum scour depth is recorded and critically is observed not to be equal to the nal depth due to signicant sediment slumping when ow velocities reduce in the latter stages of inundation. Current and wave scour predictor equations over predict the scour, while the ASCE 7-16 method under predicts. Comparisons with available data in the literature show longer inundation durations increase the amount of scour.

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Limits on Coastal Scour Depths due to Tsunami

Cited by 18 publications

References 2 publications

A New Relative Risk Index for Hospitals Exposed to Tsunami

A New Relative Risk Index for Hospitals Exposed to Tsunami

Engineering Lessons from September 28, 2018 Indonesian Tsunami: Scouring Mechanisms and Effects on Infrastructure

Experimental observations of tsunami induced scour at onshore structures

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