Effect of overflow and seepage coupling on tsunami-induced instability of caisson breakwaters

Sassa, Shinji; Takahashi, Hidenori; Morikawa, Yoshiyuki; Takano, Daiki

doi:10.1016/j.coastaleng.2016.08.004

Cited by 34 publications

(10 citation statements)

References 11 publications

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“…11, No. 1, February 2019 In the non-saturated area, the seepage analysis can be expressed as follows: (6) The equation reveals that the unsaturated soil state changes with changes in the fluid volume. The water seepage process requires a long time to analyze numerically.…”

Section: B Seepage Principles For Saturated and Unsaturated Soilmentioning

confidence: 99%

“…The relevance of the heavy rainfall and almost synchronous seismic event was investigated in one study, but the landslide was concluded to be due to progressive failure of the rock slope and tectonic weakening, with the landslide aggravated by the presence of rice paddy fields in the bottom of the valley [5]. By contrast, [6] argued that the 2006 Southern Leyte mudslide was possibly triggered due to the combined effect of the small-magnitude earthquake and the heavy rain.…”

Section: Introductionmentioning

confidence: 99%

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Combined Effect of Rainfall Seepage and Seismic Shaking on Slope Stability by Using a Three-Dimensional Stability Analysis

Chen¹,

Wu²

2019

IJET

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Taiwan is located in the Pacific Rim seismic zone and has a subtropical climate and mountainous areas. As a limited amount of area in Taiwan can be categorized as plains, the mountainous areas are used for development requirements. Overdevelopment on weak slope lands causes them to collapse and further exposes the lands to natural disasters such as earthquakes and torrential rains. Thus, appropriate slope stability analysis methods and engineering design measures should be proposed for slope lands. The purpose of this study was to discuss the combined effect of seismic shaking and soil seepage due to rainfall on slope lands by analyzing their combined effect on the factor of safety (FS) and failure mode of a slope land. A slope stability analysis was conducted using finite difference analysis, performed with FLAC3D. The soil strength reduction method was adopted to identify the FS of slopes in a static state by using FLAC3D. The formation of plastic sliding zones as the ratio of soil strength reduction was defined as FS in the seismic analysis. This study employed earthquake time history data of the Chi-Chi earthquake recorded at the Shihgang Dam station in the central region of Taiwan. The combined effect of seismic shaking and soil seepage due to rainfall was analyzed to determine its influence on the FS of the slope. The proposed method, which analyzes the combined effect of seismic shaking and rainfall seepage on the FS, obtains superior results to the conventional method, which analyzes the effects of seismic shaking and rainfall seepage separately.

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Section: B Seepage Principles For Saturated and Unsaturated Soilmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Combined Effect of Rainfall Seepage and Seismic Shaking on Slope Stability by Using a Three-Dimensional Stability Analysis

Chen¹,

Wu²

2019

IJET

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“…The water level difference also caused seepage flow across the structure of caisson breakwaters with rubble mound foundations, thus decreasing the bearing capacity [Sassa, 2014]. The general effect of seepage and the exact sequence of the failure modes require more experiments to better understand the overall damage caused by a tsunami [Sassa et al, 2016].…”

Section: Impact Loads and Failure Mechanisms Of Coastal Protection Stmentioning

confidence: 99%

Risk Assessment and Design of Prevention Structures for Enhanced Tsunami Disaster Resilience (RAPSODI)/Euro-Japan Collaboration

Harbitz

Nakamura

Arikawa

et al. 2016

Coastal Engineering Journal

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The 2011 Tōhoku event showed the massive destruction potential of tsunamis. The EuroJapan "Risk assessment and design of prevention structures for enhanced tsunami disaster resilience (RAPSODI)" project aimed at using data from the event to evaluate tsunami mitigation strategies and to validate a framework for a quantitative tsunami mortality risk analysis. Coastal structures and mitigation strategies against tsunamis in Europe and Japan are compared. Failure mechanisms of coastal protection structures exposed to tsunamis are discussed based on field data. Knowledge gaps on failure modes of different structures under different tsunami loading conditions are identified. Results of the wave-flume laboratory experiments on rubble mound breakwaters are used to assess their resilience against tsunami impact. For the risk analysis, high-resolution digital elevation data are applied for the inundation modeling. The hazard is represented by the maximum flow depth, the exposure is described by the location of the population, and the mortality is a function of flow depth and building vulnerability. A thorough search for appropriate data on the 2011 Tōhoku tsunami was performed. The results of the 2011 Tōhoku tsunami mortality hindcast for the city of Ishinomaki substantiate that the tsunami mortality risk model can help to identify high-mortality risk areas and the main risk drivers.

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“…

This paper presents some recent research advances in tsunami-seabed-structure interaction following the 2011 Tohoku Earthquake Tsunami, Japan. Role of overflow and seepage coupling is highlighted, based on the effect of tsunami-induced seepage on piping/boiling, erosion and bearing capacity decrease and failure of the rubble/seabed foundation (Takahashi et al, 2014;Sassa, 2014;Sassa et al, 2016).A new tsunami overflow-seepage-coupled centrifuge experimental system was developed and applied such that the similitudes for tsunami overflow as well as turbulent seepage flows in the mounds were satisfied in addition to the mechanical similarity between the model and the prototype.The concurrent processes of the instability involving the scour of the mound/sandy seabed, bearing capacity failure and flow of the foundation and the failure of caisson breakwaters under the overflow and seepage coupling are elucidated in the paper. The experimental results first demonstrated that the coupled overflowseepage actions promoted the development of the mound scour significantly (Fig.

…”

mentioning

confidence: 99%

“…This paper presents some recent research advances in tsunami-seabed-structure interaction following the 2011 Tohoku Earthquake Tsunami, Japan. Role of overflow and seepage coupling is highlighted, based on the effect of tsunami-induced seepage on piping/boiling, erosion and bearing capacity decrease and failure of the rubble/seabed foundation (Takahashi et al, 2014;Sassa, 2014;Sassa et al, 2016).…”

mentioning

confidence: 99%

Tsunami-Seabed-Structure Interaction From Geotechnical and Hydrodynamic Perspectives: Role of Overflow/Seepage Coupling

Sassa¹

2018

Int. Conf. Coastal. Eng.

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Effect of overflow and seepage coupling on tsunami-induced instability of caisson breakwaters

Cited by 34 publications

References 11 publications

Combined Effect of Rainfall Seepage and Seismic Shaking on Slope Stability by Using a Three-Dimensional Stability Analysis

Combined Effect of Rainfall Seepage and Seismic Shaking on Slope Stability by Using a Three-Dimensional Stability Analysis

Risk Assessment and Design of Prevention Structures for Enhanced Tsunami Disaster Resilience (RAPSODI)/Euro-Japan Collaboration

Tsunami-Seabed-Structure Interaction From Geotechnical and Hydrodynamic Perspectives: Role of Overflow/Seepage Coupling

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