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京都大学 / 新制・課程博士 / 博士(地域研究) / 甲第24015号 / 地博第294号 / 新制||地||113(附属図書館) / 京都大学大学院アジア・アフリカ地域研究研究科東南アジア地域研究専攻 / (主査)教授 三重野 文晴, 教授 河野 泰之, 准教授 小坂 康之, 教授 水野 広祐 / 学位規則第4条第1項該当 / Doctor of Area Studies / Kyoto University / DGAM

This thesis examines the 2018 failure of the Northern Tailings Storage Facility at Cadia Valley Operations, located in New South Wales, Australia. First, the importance of examining and understanding failure mechanisms and post failure kinematics is described. Within which we understand that in the current state of affairs it is exceedingly difficult, or nigh impossible to perform without the use of large strain analyses, which have yet to permeate into the industry to a significant degree. Second, the initial construction and state of the dam just prior to failure is defined, with the materials and their properties laid out and discussed in depth as well as our means of modeling their behavior. Third, we validate and discuss our results of the base model of the dam based on key topographic features from initial and post-failure field measurements. After validation, we examine the influences of each of the different materials on the runout, comparing final topographies of different simulations with the actual final topography observed. This study was a valuable method of validating the Material Point Method as a means of modeling large deformations, as well as demonstrating its powerful applications towards catastrophic disaster prevention. The study validates and provides a greater understanding of the event of the Cadia Tailings Storage Facility Failure, and presents a framework of steps to perform similar examination on future tailings dams as a means of providing risk management in the event of failure. / Master of Science / Tailings dams are structures integral to the life cycle of mining and mineral processing. After mining and the processing of mined materials, the leftover material, known as "tailings" are pumped and stored behind these structures, usually indefinitely. These structures are unique because they are usually expanded as additional storage space for these materials is required. Over the past several decades, the rate at which catastrophic or serious tailings dam failures occur out of failures has been on the rise. Because of this, it becomes necessary to better understand the failure and post-failure movements of the dam. This thesis presents one such failure, the Cadia Tailings Dam Failure of 2018, which is located in New South Wales, Australia. It applies the Material Point Method, a numerical method which allows for largestrain deformations, to examine the post-failure mechanism and interpret various influences by the different materials on the final runout. Because of this, the paper provides insights on the importance of understanding large strain analyses, discussing and presenting the incidents of the failure. The model used for reference is validated using topographic and field data taken after the failure, allowing for a comparison with future models which vary the geometry and material characteristics of the event. A procedural plan is proposed to apply to future analyses, allowing for the analysis to be applied to other events and tailings dam structures, for further insight on influences of variability and material properties on post-failure topography and geometry.

Yes / Large amount of sediment deposits in the reservoir area can cause dam break, which not only leads to an immeasurable loss to the society, but also the sediments from the reservoir can be transported to generate further problems in the downstream catchment. This study aims to investigate the short-to-long term sediment transport and channel meandering process under such a situation. A coupled explicit-implicit technique based on the Euler-Lagrangian method (ELM) is used to solve the hydrodynamic equations, in which both the small and large time steps are used separately for the fluid and sediment marching. The main feature of the model is the use of the Characteristic-Based Split (CBS) method for the local time step iteration to correct the ELM traced lines. Based on the solved flow field, a standard Total Variation Diminishing (TVD) finite volume scheme is applied to solve the sediment transportation equation. The proposed model is first validated by a benchmark dambreak water flow experiment to validate the efficiency and accuracy of ELM modelling capability. Then an idealized engineering dambreak flow is used to investigate the long-term downstream channel meandering process with nonuniform sediment transport. The results showed that both the hydrodynamic and morphologic features have been well predicted by the proposed coupled model. / This research work is supported by Sichuan Science and Technology Support Plan (2014SZ0163), Start-up Grant for the Young Teachers of Sichuan University (2014SCU11056), and Open Research Fund of the State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University (SKLH 1409; 1512).

On December 24, 1924, a wall of water and alkali muck engulfed Palmertown, a small community in Saltville, Virginia. Houses were swept away and by the time all of the bodies were pulled from the wreckage, the death toll had reached 19-an immense loss for the tight-knit community. A dam, owned by Mathieson Alkali Works, loomed approximately 100 feet above Palmertown, keeping at bay the chemical muck produced by the company plants. Despite the extent of the damage, the flood is largely absent from discourse and no historical marker exists to memorialize the tragedy. Furthermore, Palmertown and neighboring Henrytown were expunged in the mid-twentieth century when Olin Corporation rebuilt the dam overtop of the town sites. Stories of the event have been passed down for generations, immortalizing a specific story of the disaster in the memories of many local residents of Saltville, so why is it not memorialized? The cultural framework of Saltville determined how and why this disaster and others have been remembered or forgotten. In 1924, Saltville residents were accustomed to tragic events; to some extent these events were seen as part and parcel of life in a company town in Appalachia. Yet, nearly a century after the tragedy, the process of unearthing of difficult events can illuminate much of the community's collective history and restore the fragmented communal memory. The memorialization of the Palmertown Tragedy of 1924 establishes a framework for acknowledging an arduous past and identifying the roots of a town's resilience. / Master of Arts

Tesis por compendio / Large dams are critical infrastructures whose failure could produce high economic and social consequences. For this reason, in recent years, the application of quantitative risk analysis to inform dam safety governance has risen significantly worldwide. This thesis is focused in how computed quantitative risk results can be useful to inform dam safety management. It proposes different methods and metrics to deal with the two key issues identified in this process: how risk results can be managed to prioritize potential investments and how uncertainty should be considered in quantitative risk models to inform decision making. Firstly, it is demonstrated that risk reduction indicators are a useful tool to obtain prioritization sequences of potential safety investments, especially in portfolios with a high number of dams. Different indicators for dam safety are assessed, analyzing their relation with equity and efficiency principles. Secondly, it is proposed to consider explicitly and independently natural and epistemic uncertainty in quantitative risk models for dams, following the recommendations developed by other industries. Specifically, a procedure is developed to separate both types of uncertainty in the fragility analysis for the sliding failure mode of gravity dams. Finally, both issues are combined to propose different metrics that analyze the effect of epistemic uncertainty in the prioritization of investments based on risk results. These metrics allow considering the convenience of conducting additional uncertainty reduction actions, like site tests, surveys or more detailed analysis. / Las grandes presas son infraestructuras críticas cuyo fallo puede producir importantes consecuencias económicas y sociales. Por este motivo, en los últimos años la aplicación de técnicas de análisis de riesgos para informar a la gobernanza de la seguridad de presas se ha extendido por todo el mundo. La presente tesis se centra en analizar cómo los resultados calculados de riesgo pueden ser útiles para la toma de decisiones en seguridad de presas. Para ello, se proponen diferentes métodos e indicadores que tratan los dos principales problemas identificados en este proceso: cómo gestionar los resultados de riesgo para priorizar potenciales inversiones en seguridad y cómo debe ser considerada la incertidumbre en los modelos de riesgo para orientar a la toma de decisiones. En primer lugar, se muestra como los indicadores de reducción de riesgo son una herramienta útil y eficaz para obtener secuencias de priorización de potenciales medidas de reducción de riesgo, especialmente en la gestión conjunta de grandes grupos de presas. Por ello, los diferentes indicadores para la gestión de la seguridad de presas son evaluados, analizando su relación con los principios de eficiencia y equidad. En segundo lugar, se propone considerar la incertidumbre epistémica y la incertidumbre natural de forma independiente dentro de los modelos de riesgo cuantitativos para presas, siguiendo las recomendaciones de otras industrias. En particular, se propone un procedimiento para separar ambos tipos de incertidumbre en el análisis del modo de fallo por deslizamiento en presas de gravedad. Finalmente, ambos puntos se combinan para proponer diferentes índices que analicen la influencia de la incertidumbre epistémica sobre las secuencias de priorización obtenidas mediante indicadores de reducción de riesgo, y por lo tanto, sobre la toma de decisiones. De esta forma, estos índices permiten analizar la necesidad de realizar acciones adicionales para reducir la incertidumbre epistémica, como ensayos, sondeos o estudios detallados. / Les grans preses son infraestructures crítiques que si fallen poden produir importants conseqüències econòmiques i socials. Per aquest motiu, en el últims anys la aplicació de tècniques d'anàlisis de rics per a informar a la governança de seguretat de preses s'ha estès per tot el món. Aquesta tesi es centra en analitzar com els resultats calculats de risc poden ser útils per a prendre decisions en seguretat de preses. Per a això, es proposen diferents mètodes i indicadors que tracten el dos principals problemes identificats en aquest procés: com gestionar els resultats de risc per a prioritzar potencials inversions en seguretat i com el models de risc han de considerar la incertesa per a orientar a la presa de decisions. En primer lloc, es mostra com el indicadors de reducció de riscs son una ferramenta útil i eficaç per a obtindré seqüències de priorització de potencials mesures de reducció de risc, especialment en la gestió conjunta de grans grups de preses. Per això, els diferents indicadors per a la gestió de la seguretat de preses son avaluats, analitzant la seua relació amb els principis d'eficiència i equitat. En segon lloc, es proposa considerar la incertesa natural i la incertesa epistèmica de forma independent dintre del models quantitatius de risc per a preses, seguint les recomanacions d'altres industries. En particular, es proposa un procediment per a separar el dos tipus d'incertesa en el anàlisis del fall per lliscament en preses de gravetat. Finalment, el dos punts es combinen per a proposar índexs que analitzen la influència de la incertesa epistèmica sobre les seqüencies de priorització de mesures obtingudes amb els indicadors de reducció de risc, y per tant, sobre la presa de decisions. D'aquesta forma, aquests índexs permeten analitzar la necessitat de realitzar acciones per a reduir la incertesa, como assajos, sondejos geotècnics o estudis de detall. / Morales Torres, A. (2017). Evaluation of the impact of risk reduction indicators and epistemic uncertainty in dam safety governance [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/79739 / Compendio

No / An incompressible smoothed particle hydrodynamics (SPH) method is presented to simulate Newtonian and non-Newtonian flows with free surfaces. The basic equations solved are the incompressible mass conservation and Navier¿Stokes equations. The method uses prediction¿correction fractional steps with the temporal velocity field integrated forward in time without enforcing incompressibility in the prediction step. The resulting deviation of particle density is then implicitly projected onto a divergence-free space to satisfy incompressibility through a pressure Poisson equation derived from an approximate pressure projection. Various SPH formulations are employed in the discretization of the relevant gradient, divergence and Laplacian terms. Free surfaces are identified by the particles whose density is below a set point. Wall boundaries are represented by particles whose positions are fixed. The SPH formulation is also extended to non-Newtonian flows and demonstrated using the Cross rheological model. The incompressible SPH method is tested by typical 2-D dam-break problems in which both water and fluid mud are considered. The computations are in good agreement with available experimental data. The different flow features between Newtonian and non-Newtonian flows after the dam-break are discussed.