Antonio Abellan | University of Cambridge (original) (raw)

Uploads

Papers by Antonio Abellan

The study area is located in the easternmost sector of the Betic Cordillera which corresponds to ... more The study area is located in the easternmost sector of the Betic Cordillera which corresponds to the named Prebetic of Alicante (Spain). This area is characterized by the predominance of carbonatic and marly lithologies from Jurassic to Quaternary and wide gypsiferous diapiric Triassic outcrops. Finestrat urban area is just placed over one diapiric which is delimited at south and west by steep slopes mainly composed by Triassic lithologies. This work analyses the displacements of a gypsiferous slope located in the town of Finestrat, Alicante (SE Spain) and the buildings placed on its crown by means of a Terrestrial Laser Scanner (TLS). Finestrat, located near Benidorm, is a major tourist attraction. Most of the town is placed over a steep relief with a heigh up to 30 meters mainly composed of massive Keuper Triassic gypsums with alternating layers of clay and sandstones. Gypsum rock falls are frequent on the whole slope as shown by previous rockfall historical records of the slope. ...

Investigation of fractured rock masses for different geological applications (e.g. fractured rese... more Investigation of fractured rock masses for different geological applications (e.g. fractured reservoir exploitation, rock slope instability, rock engineering, etc.) requires a deep geometric understanding of the discontinuity sets affecting rock exposures. Recent advances in 3D data acquisition using photogrammetric and/or LiDAR techniques currently allow a quick and an accurate characterization of rock mass discontinuities. This contribution presents a methodology for: (a) use of 3D point clouds for the identification and analysis of planar surfaces outcropping in a rocky slope; (b) calculation of the spacing between different discontinuity sets; (c) semi-automatic calculation of the parameters that play a capital role in the Slope Mass Rating geomechanical classification. As for the part a) (discontinuity orientation), our proposal identifies and defines the algebraic equations of the different discontinuity sets of the rock slope surface by applying an analysis based on a neighbo...

Little is known about the characteristics (magnitude, frequency, spatial location, etc) of precur... more Little is known about the characteristics (magnitude, frequency, spatial location, etc) of precursory rockfalls leading to larger failures. In order to better understand this phenomena, we investigated the spatial location of precursory rockfalls and how these events tends to concentrate along the cracks that define the boundaries of the area were a larger failure will took place. Once a certain mass movement has started, the higher stress is concentrated around the limits between the moving and the stables parts of the slope, i.e. the limits between the ongoing rockfall and the rest of the slope. Since natural rock slopes do not allow too much deformation to be produced, the stress on the rock slope surface is expressed in surface by the occurrence of a series of rockfalls along time. Indeed, similar behaviour is observed in other geological events as earthquakes, which distribution is concentrated along the area of higher stress, i.e. along the tectonic plate boundaries. We carrie...

RESUMEN En este estudio se presenta un sencillo modelo predictivo de la velocidad de un deslizami... more RESUMEN En este estudio se presenta un sencillo modelo predictivo de la velocidad de un deslizamiento en función de la precipitación. El modelo se ha aplicado al deslizamiento de Vallcebre (Pirineo oriental), un movimiento de ladera activo con una tasa de desplazamiento lenta (con una media de 25cm/año) y variable a lo largo del tiempo en función del nivel freático. El modelo conceptual está basado en la creación de una función de transferencia para modelizar la influencia del agua que se infiltra en el terreno sobre la velocidad del deslizamiento. Dicha función de transferencia ha sido creada con una geometría de tipo exponencial para explicar la infiltración de agua en el terreno siguiendo las leyes de comportamiento enunciadas por Kostiakov (1932) y Horton (1933), formulas ampliamente utilizadas en hidrología subterránea. De este modo, la tasa de desplazamiento se calcula, para cada unidad de tiempo (día), como una suma de cada uno de los productos (convolución) de la función de ...

Current challenges in landslide forecasting include the development of new techniques to predict ... more Current challenges in landslide forecasting include the development of new techniques to predict rockfalls in natural slopes using a certain precursory indicator as precursory rockfalls leading to larger failures, micro-seismic events, precursory deformation, etc. Regarding small scale pre-failure deformation leading to larger failures, current techniques fail to detect this indicator due to insufficient data accuracy and/or low temporal resolution (infrequent data acquisition). To understand the precursory phenomena in non-cohesive soils, we carried out a series of experimental tests with analogue model. These tests are realized in a sandbox with both sides made of glass, allowing visualisation of the failure planes. For the simulation, a 50 cm vertical slope was built with quartz sand with a fixed percentage of bentonite. Measurements were carried out using 3D remote sensing techniques (Konica digitizer Minolta Vivid 9i) to acquire to acquire high accuracy (± 0.05 mm) and high res...

Landslides, 2015

ABSTRACT A detailed analysis of the pre-failure behavior of the 3 December 2013 rockfall (1,012 m... more ABSTRACT A detailed analysis of the pre-failure behavior of the 3 December 2013 rockfall (1,012 m3) occurred on Puigcercós pilot study area (Catalonia, Spain) is presented. The exact date of failure was obtained based on a photographic monitoring performed every 4 h. The long-term monitoring (2,217 days) of the rock slope carried out by a Terrestrial LiDAR allowed the early detection of both pre-failure deformation and precursory rockfalls preceding the final failure. By means of the analysis of the pre-failure deformation, four different deformed areas were detected and the tertiary creep phase was observed in three of them. An attempt to predict the time to failure was performed using the Fukuzono’s (1985) method. Furthermore, the temporal evolution of the precursory rockfalls occurred in those four areas during the progressive failure showed a close resemblance with the exponential pattern of the cumulated displacements at tertiary creep stage. Finally, the study of the meteorological conditions did not show any single triggering factor associated with the final failure. Reversely, the increase in the occurrence of precursory rockfalls on several areas of the slope together with the observed acceleration on the deformation pattern reinforce the role of a progressive degradation of the stability conditions, which ultimately leaded to the 3 December rockfall event.

The acquisition of dense terrain information using well-established 3D techniques (e.g. LiDAR, ph... more The acquisition of dense terrain information using well-established 3D techniques (e.g. LiDAR, phtogrammetry) and the use of new mobile platforms (e.g. Unmanned Aerial Vehicles) together with the increasingly efficient post-processing workflows for image treatment (e.g. Structure From Motion) are opening up new possibilities for analysing, modeling and predicting rock slope failures. Examples of applications at different scales ranging from the monitoring of small changes at unprecedented level of detail (e.g. sub millimeter-scale deformation under lab-scale conditions) to the detection of slope deformation at regional scale. In this communication we will show the main accomplishments of the Swiss National Foundation project “Characterizing and analysing 3D temporal slope evolution“ carried out at Risk Analysis group (Univ. of Lausanne) in close collaboration with the RISKNAT and INTERES groups (Univ. of Barcelona and Univ. of Alicante, respectively). We have recently developed a se...

The study area is located in the easternmost sector of the Betic Cordillera which corresponds to ... more The study area is located in the easternmost sector of the Betic Cordillera which corresponds to the named Prebetic of Alicante (Spain). This area is characterized by the predominance of carbonatic and marly lithologies from Jurassic to Quaternary and wide gypsiferous diapiric Triassic outcrops. Finestrat urban area is just placed over one diapiric which is delimited at south and west by steep slopes mainly composed by Triassic lithologies. This work analyses the displacements of a gypsiferous slope located in the town of Finestrat, Alicante (SE Spain) and the buildings placed on its crown by means of a Terrestrial Laser Scanner (TLS). Finestrat, located near Benidorm, is a major tourist attraction. Most of the town is placed over a steep relief with a heigh up to 30 meters mainly composed of massive Keuper Triassic gypsums with alternating layers of clay and sandstones. Gypsum rock falls are frequent on the whole slope as shown by previous rockfall historical records of the slope. ...

Investigation of fractured rock masses for different geological applications (e.g. fractured rese... more Investigation of fractured rock masses for different geological applications (e.g. fractured reservoir exploitation, rock slope instability, rock engineering, etc.) requires a deep geometric understanding of the discontinuity sets affecting rock exposures. Recent advances in 3D data acquisition using photogrammetric and/or LiDAR techniques currently allow a quick and an accurate characterization of rock mass discontinuities. This contribution presents a methodology for: (a) use of 3D point clouds for the identification and analysis of planar surfaces outcropping in a rocky slope; (b) calculation of the spacing between different discontinuity sets; (c) semi-automatic calculation of the parameters that play a capital role in the Slope Mass Rating geomechanical classification. As for the part a) (discontinuity orientation), our proposal identifies and defines the algebraic equations of the different discontinuity sets of the rock slope surface by applying an analysis based on a neighbo...

Little is known about the characteristics (magnitude, frequency, spatial location, etc) of precur... more Little is known about the characteristics (magnitude, frequency, spatial location, etc) of precursory rockfalls leading to larger failures. In order to better understand this phenomena, we investigated the spatial location of precursory rockfalls and how these events tends to concentrate along the cracks that define the boundaries of the area were a larger failure will took place. Once a certain mass movement has started, the higher stress is concentrated around the limits between the moving and the stables parts of the slope, i.e. the limits between the ongoing rockfall and the rest of the slope. Since natural rock slopes do not allow too much deformation to be produced, the stress on the rock slope surface is expressed in surface by the occurrence of a series of rockfalls along time. Indeed, similar behaviour is observed in other geological events as earthquakes, which distribution is concentrated along the area of higher stress, i.e. along the tectonic plate boundaries. We carrie...

RESUMEN En este estudio se presenta un sencillo modelo predictivo de la velocidad de un deslizami... more RESUMEN En este estudio se presenta un sencillo modelo predictivo de la velocidad de un deslizamiento en función de la precipitación. El modelo se ha aplicado al deslizamiento de Vallcebre (Pirineo oriental), un movimiento de ladera activo con una tasa de desplazamiento lenta (con una media de 25cm/año) y variable a lo largo del tiempo en función del nivel freático. El modelo conceptual está basado en la creación de una función de transferencia para modelizar la influencia del agua que se infiltra en el terreno sobre la velocidad del deslizamiento. Dicha función de transferencia ha sido creada con una geometría de tipo exponencial para explicar la infiltración de agua en el terreno siguiendo las leyes de comportamiento enunciadas por Kostiakov (1932) y Horton (1933), formulas ampliamente utilizadas en hidrología subterránea. De este modo, la tasa de desplazamiento se calcula, para cada unidad de tiempo (día), como una suma de cada uno de los productos (convolución) de la función de ...

Current challenges in landslide forecasting include the development of new techniques to predict ... more Current challenges in landslide forecasting include the development of new techniques to predict rockfalls in natural slopes using a certain precursory indicator as precursory rockfalls leading to larger failures, micro-seismic events, precursory deformation, etc. Regarding small scale pre-failure deformation leading to larger failures, current techniques fail to detect this indicator due to insufficient data accuracy and/or low temporal resolution (infrequent data acquisition). To understand the precursory phenomena in non-cohesive soils, we carried out a series of experimental tests with analogue model. These tests are realized in a sandbox with both sides made of glass, allowing visualisation of the failure planes. For the simulation, a 50 cm vertical slope was built with quartz sand with a fixed percentage of bentonite. Measurements were carried out using 3D remote sensing techniques (Konica digitizer Minolta Vivid 9i) to acquire to acquire high accuracy (± 0.05 mm) and high res...

Landslides, 2015

ABSTRACT A detailed analysis of the pre-failure behavior of the 3 December 2013 rockfall (1,012 m... more ABSTRACT A detailed analysis of the pre-failure behavior of the 3 December 2013 rockfall (1,012 m3) occurred on Puigcercós pilot study area (Catalonia, Spain) is presented. The exact date of failure was obtained based on a photographic monitoring performed every 4 h. The long-term monitoring (2,217 days) of the rock slope carried out by a Terrestrial LiDAR allowed the early detection of both pre-failure deformation and precursory rockfalls preceding the final failure. By means of the analysis of the pre-failure deformation, four different deformed areas were detected and the tertiary creep phase was observed in three of them. An attempt to predict the time to failure was performed using the Fukuzono’s (1985) method. Furthermore, the temporal evolution of the precursory rockfalls occurred in those four areas during the progressive failure showed a close resemblance with the exponential pattern of the cumulated displacements at tertiary creep stage. Finally, the study of the meteorological conditions did not show any single triggering factor associated with the final failure. Reversely, the increase in the occurrence of precursory rockfalls on several areas of the slope together with the observed acceleration on the deformation pattern reinforce the role of a progressive degradation of the stability conditions, which ultimately leaded to the 3 December rockfall event.

The acquisition of dense terrain information using well-established 3D techniques (e.g. LiDAR, ph... more The acquisition of dense terrain information using well-established 3D techniques (e.g. LiDAR, phtogrammetry) and the use of new mobile platforms (e.g. Unmanned Aerial Vehicles) together with the increasingly efficient post-processing workflows for image treatment (e.g. Structure From Motion) are opening up new possibilities for analysing, modeling and predicting rock slope failures. Examples of applications at different scales ranging from the monitoring of small changes at unprecedented level of detail (e.g. sub millimeter-scale deformation under lab-scale conditions) to the detection of slope deformation at regional scale. In this communication we will show the main accomplishments of the Swiss National Foundation project “Characterizing and analysing 3D temporal slope evolution“ carried out at Risk Analysis group (Univ. of Lausanne) in close collaboration with the RISKNAT and INTERES groups (Univ. of Barcelona and Univ. of Alicante, respectively). We have recently developed a se...