Coefficient of restitution and rotational motions of rockfall impacts

Chau, Kam Tim; Wong, Ryc; Wu, Jia-Rung

doi:10.1016/s1365-1609(02)00016-3

Cited by 265 publications

(175 citation statements)

References 10 publications

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“…En el modelo de desprendimientos que actualmente desarrolla nuestro grupo se hace hincapié en la importancia de considerar la fractura del bloque que está cayendo. Sabemos que el mecanismo de fragmentación de una masa rocosa no es trivial (Zang et al 2000;Chau et al 2002) y que son diversos los parámetros que afectan la fragmentación de un bloque (Wang and Tonon 2011): la presencia de discontinuidades, incluyendo la persistencia y la orientación, la energía del impacto, la rigidez del terreno y el ángulo de incidencia del impacto afectan el modo de disgregación en fragmentos. A su vez e independientemente, cada fragmento seguirá cayendo, rodando y probablemente fragmentándose de nuevo.…”

Section: Determinación De Trayectorias De Bloques Rocosos En Ensayos unclassified

Determinación De Trayectorias De Bloques Rocosos en Ensayos Mediante Videogrametría

Matas¹,

Núñez-Andrés²,

Pozuelo³

et al. 2017

Proceedings - 1st Congress in Geomatics Engineering - CIGeo

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Abstract:Determining the trajectory of a block that falls down on a slope is not straightforward due to the high number of variables involved. Because of this, the appropriate understanding of how these variables may affect the trajectories is required.In this work, we estimate some magnitudes that affect the trajectories of the blocks such as the coefficient of restitution and the energy thresholds for fragmentation of the blocks among others. We have chosen the controlled scenario of a quarry in which targets and high speed video cameras were arranged to capture images of the blocks falling from the top of a slope. The position of the blocks over time has been measured from video frames applying photogrammetric methods. From here, the velocities and the accelerations have been determined, and with the estimated mass of each block, we have calculated the energy balance.Key words: Geomatics, Photogrammetry, Videogrammetry, 3D Models, Rock falls. Resumen:La trayectoria de un bloque que cae por un talud no es fácil de determinar porque influyen muchas variables difíciles de cuantificar. Ello requiere del conocimiento de cómo estas variables afectan a las trayectorias.En este trabajo se estiman algunas magnitudes que afectan la trayectoria de los bloques como son los coeficientes de restitución y los límites de energía para generar la fragmentación del bloque, entre otros. Para ello se ha escogido el entorno controlado de una cantera, en el que se han dispuesto dianas y cámaras de vídeo de alta velocidad, para capturar imágenes de las caídas de bloques lanzados desde lo alto de un talud. Hemos medido la posición del bloque respecto del tiempo a partir de los fotogramas de vídeo obtenidos, aplicando métodos fotogramétricos. A partir de aquí se determinan las velocidades y las aceleraciones y, con la estimación de la masa de cada bloque, hemos calculado los balances de energía.

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Section: Determinación De Trayectorias De Bloques Rocosos En Ensayos unclassified

Determinación De Trayectorias De Bloques Rocosos en Ensayos Mediante Videogrametría

Matas¹,

Núñez-Andrés²,

Pozuelo³

et al. 2017

Proceedings - 1st Congress in Geomatics Engineering - CIGeo

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“…9). In most cases, the amount of rotational energy represents just a small fraction of the total kinetic energy (Chau et al 2002), so only the translational motion parameters of the block are considered. The impact action is assumed to be applied horizontally, normal to the face of a column.…”

Section: Applicationmentioning

confidence: 99%

Vulnerability of simple reinforced concrete buildings to damage by rockfalls

Mavrouli

Corominas

2010

Landslides

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A procedure is presented for investigating the response of reinforced concrete buildings to rockfall impact. The method considers a single rock hit on the basement columns, and it includes four steps: (a) calculation of the probability of a rock impact on a member of the load-bearing system, taking into account the block size and the design of the structure; (b) evaluation of the response of one or more structural elements to the hit based on element capacity; (c) in the case of structural element failure, assessment of the robustness of the whole structural system, calculating the potential for progressive collapse; and (d) calculation of a damage index (DI), which is the ratio of structural elements that fail to the total number of structural elements. The proposed method is applied to a reinforced concrete building for a range of rockfall paths and intensities. The analysis has been carried out for a 2-m-diameter block and velocities< 3.5 m/s. The possible damage range is found to be highly variable, with DI values ranging from 0.01 to 1 depending on the impact location and block velocity.

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“…In addition, there is an epistemic uncertainty because of the limited basis for estimating the model parameters (see e.g. Robotham et al (1995), Azzoni et al (1995) and Chau et al (2002) for an estimation of coefficients of restitution). Additional epistemic uncertainty is due to the simplified modeling of the slope profile at the impact location.…”

Section: Uncertainties In Rock-fall Trajectorymentioning

confidence: 99%

Modeling and managing uncertainties in rock-fall hazards

Straub

Schubert

2008

Georisk: Assessment and Management of Risk for Engineered Syste

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The assessment of rock-fall hazards is subject to significant uncertainty, which is not fully considered in general practice and research. This paper reviews and classifies the various sources of the uncertainty. Taking a generic framework for risk assessment as source, a probabilistic model is presented that consistently combines the different types of uncertainties, in order to obtain a unified estimate of rock-fall risk. An important aspect of the model is that it allows for incorporating all available information, including physical and empirical models, observations and expert knowledge, by means of Bayesian updating. Detailed formulations are developed for various types of information. Finally, two examples considering rock-fall risk on roads, with and without protection structures, illustrate the application of the probabilistic modeling framework to practical problems.

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Coefficient of restitution and rotational motions of rockfall impacts

Cited by 265 publications

References 10 publications

Determinación De Trayectorias De Bloques Rocosos en Ensayos Mediante Videogrametría

Determinación De Trayectorias De Bloques Rocosos en Ensayos Mediante Videogrametría

Vulnerability of simple reinforced concrete buildings to damage by rockfalls

Modeling and managing uncertainties in rock-fall hazards

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