Effect of rockfall fragmentation on exposure and subsequent risk analysis

Rockfalls are frequent natural processes in mountain regions with the potential to produce damage. The quantitative risk analysis (QRA) is an approach increasingly used to assess risk and evaluate the performance of mitigation measures. In case of the fragmentation of the falling rock mass, some of the hypothesis taken in the QRA estimation for rockfalls have to be modified since a single block or rock mass can produce several fragments thus modifying the runout probability, the impact energies and exposure of the elements at risk. In this contribution, we present a procedure to account for the exposure in QRA analysis along linear paths using the fragmental rockfall propagation model RockGIS (Matas et al. 2017). The procedure is applied at the “Monasterio de Piedra”, Spain as part of a QRA.Postprint (published version

3D analysis of a fragmental rockfall

The final authenticated version is available online at https://doi.org/10.1007/978-3-030-60706-7_15.Fragmentation in a rockfall event influence the total number of fragments, the mass distribution, and the impact energies and runouts. Then, the probability of impact and hazard characterization should consider fragmentation. A fractal fragmentation model has been proposed in order to reproduce the phenomenon. The Rockfall Fractal Fragmentation Model has been implemented in a 3D rockfall propagation simulator named RockGIS. We present the analysis of a fragmental rockfall that occurred in Mallorca, Spain. Fieldworks are carried out in order to obtain the block size distribution of the rockfall deposit. A 3D terrain model is obtained using UAV surveys and digital photogrammetric techniques. The obtained 3D point cloud is cleaned of vegetation and used to create a Digital Elevation Model (DEM). The fragmentation model parameters and the propagation simulator coefficients have been calibrated to accomplish both, the resultant block size distribution and the runout distance of the blocks. The obtained results show a good reproduction of the fragmental rockfall studied. After the calibration is accomplished, older and future rockfalls in the cliff may be analyzed, considering thousands or single blocks simulations with or without fragmentation.This study was supported by the research project RockModels (Ref.BIA2016-75668-P, AEI/FEDER.UE) funded by the Spanish Ministry of Economy and Competitiveness. Acknowledge also, to the local government of Mallorca (Balearic Islands, Spain).Postprint (author's final draft

Estudio de las fábricas de harinas de finales del siglo XIX y principios del siglo XX. Análisis arquitectónico y reconstrucción gráfica de estas edificaciones en la provincia de Albacete

La fábrica de harinas “Fontecha y Cano” de Albacete, fundada en 1916, es una edificación perteneciente a la tipología de “fábrica de pisos” tan presente en la construcción fabril de comienzos de la Revolución Industrial, que llega al interior de la península a finales del siglo XIX y principios del siglo XX. Es el único testimonio que queda en pie del pasado industrial reciente de la ciudad. En la edificación original, coexisten los materiales y los modos tradicionales de albañilería con las nuevas técnicas de construcción provenientes de la utilización de los, entonces, novedosos elementos estructurales producidos industrialmente a partir de los derivados del hierro. La fábrica de harinas formaba parte de un conjunto industrial ubicado dentro de un recinto vallado. En el recinto se encontraba la fábrica propiamente dicha, destinada al proceso de fabricación, y otros edificios anejos, de arquitectura menor, destinados a actividades complementarias de la industria. En 1920, cuatro años después de la puesta en funcionamiento del complejo industrial, se construyó, aneja al recinto, una barriada obrera destinada a dar alojamiento a los trabajadores de la fábrica. Repetición, a pequeña escala, de las colonias obreras que proliferaron en Europa en los años de la Revolución Industrial. En sus mejores años, la factoría llegó a tener una producción de harinas superior a sesenta mil kilos diarios. Por sus dimensiones y características, fue fábrica de referencia en la provincia de Albacete. La fábrica cesó su actividad a finales de los años 80 del siglo XX, y con su cierre comienza una degradación del sitio industrial. El complejo y la barriada obrera siguieron suertes diferentes. Por un lado, en el interior del recinto se autorizó la construcción de edificación residencial de nueva planta, lo que implicó la desaparición de los edificios anejos, de menor importancia. Del recinto solo quedó como vestigio industrial el edifico de la fábrica. Su interior fue rápidamente desmantelado, desapareció la maquinaria y permaneció la arquitectura que la contuvo, quedando en estado de abandono y progresivo deterioro hasta el año 2000 en el que, en estado casi ruinoso, fue rehabilitado para uso administrativo. La rehabilitación implicó la destrucción de los elementos de la edificación no aprovechables para el nuevo uso y la incorporación de nuevos volúmenes aptos para el uso futuro, con la consiguiente modificación de la morfología original del edificio. Por otro lado, las viviendas obreras quedaron desvinculadas del recinto industrial y fueron absorbidas en la nueva trama urbana que las integró en calles de nuevo trazado, desvirtuando el carácter unitario primitivo de la barriada. Muchas de esas viviendas se encuentran hoy desaparecidas. El sitio industrial hubiera merecido ser considerado “Patrimonio Industrial” de Albacete, sin embargo, en su día no se tuvieron en cuenta los valores del conjunto como herencia cultural y testimonio de la industrialización de la ciudad. Únicamente se ha mantenido en pie, a salvo de la desaparición, el edificio principal por su consideración de monumento aislado. El objeto del presente trabajo es poner en valor el carácter patrimonial del sitio industrial, hoy desaparecido, así como su rescate documental y el análisis formal y constructivo de las edificaciones que formaron parte de él. El análisis en profundidad de los elementos construidos del sitio industrial, ha exigido unos trabajos previos de contextualización del hecho arquitectónico, que han consistido en el estudio y análisis de las circunstancias históricas, económicas, técnicas y sociales que circunscribieron su ejecución. A partir de los planos que forman parte de la documentación gráfica resultante de este trabajo, en los que se define el sitio industrial, se ha procedido a un ejercicio de diseño y modelado con la ayuda de programas de diseño gráfico específicos, con el objeto de recrear la imagen virtual de lo que fuera el sitio industrial.The Fontecha y Cano Flour Factory (Fábrica de Harinas Fontecha y Cano), founded in Albacete, in 1916, is a multi-storey factory building, a variety of factory construction typical of the beginning of the Industrial Revolution. This type of factory started to be built in the interior of the Iberian Peninsula at the end of the 19th and beginning of the 20th century. It is the only remaining testimony of the city’s recent industrial past. In the original building, traditional masonry materials and methods combined with new building techniques that originated from the then novel structural elements industrially produced using iron-based products. The flour factory formed part of an industrial complex situated within fenced grounds. The grounds contained the factory itself, devoted to the manufacturing process, and other less architecturally sophisticated outbuildings, dedicated to complementary industrial activities. In 1920, four years after the industrial complex started operating, a neighbourhood of working class homes was built next to the grounds to house factory workers. This was a small-scale imitation of the workers’ colonies which proliferated in Europe during the Industrial Revolution. In its heyday, the factory produced more than sixty thousand kilos of flour a day. Its dimensions and characteristics made it the benchmark for factories in the province of Albacete. The factory ceased its activity at the end of the nineteen-eighties, and its closure marked the beginning of the deterioration of the industrial site. The complex and the workers’ neighbourhood suffered different fates. On one hand, the construction of residential buildings was authorised within the grounds, involving the demolition of the outbuildings, which were of less architectural interest. The only industrial remnant of the complex was the factory building. The factory’s interior was rapidly dismantled and the machinery disappeared, leaving only the architectural shell. This was left in a state of neglect and gradually deteriorated until the year 2000, when, almost in ruins, it was renovated for use as offices. The renovation work involved the destruction of the elements that could not be utilised in the new version of the building and the introduction of new volumes adapted to the future use, resulting in a modification of the original morphology of the building. On the other hand, the workers’ homes were no longer part of the industrial complex, and were absorbed into the new urban layout, which integrated them into newly designed streets, distorting the previous homogenous nature of the neighbourhood. Many of these houses have since disappeared. The site would have been worthy of consideration as an Albacete Industrial Heritage Site. At the time, however, scant attention was given to the value of the complex as cultural heritage and a testimony to the city’s industrialisation. The main building is the only part to remain standing, saved from demolition due to its status as an individual monument. The aim of the present work is to showcase the heritage characteristics of this “industrial site”, which has now disappeared, as well as the rescued documents and the formal and constructive analysis of the buildings forming the complex. The in-depth analysis of the elements of the industrial site has required prior work to contextualise the architectural process. This work involved the study and analysis of the historical, economic, technical and social circumstances impacting on the execution of the site. Drawing on the plans which form part of the graphic documentation of this study and which define the layout of the complex, specific graphic design programmes were used to design, model and recreate a virtual image of what was once the industrial site

Implementation of a fixed-location time lapse photogrammetric rock slope monitoring system in Castellfollit de la Roca, Spain

When monitoring deformations in natural hazards such as rockfalls and landslides, the use of 3D models has become a standard. Several geomatic techniques allow the generation of these models. However, each one has its pros and cons regarding accuracy, cost, sample frequency, etc. In this contribution a fixed-location time lapse camera system for continuous rockfall monitoring using photogrammetry has been developed as an alternative to Light Detection and Ranging (LiDAR) and ground-based interferometric synthetic-aperture radar (GB-InSAR). The usage of stereo photogrammetry allows the obtention of 3D points clouds at a low cost and with a high sample frequency, essential to detect premonitory displacements. In this work the designed system consists of three digital single-lens reflex (DSLR) cameras which collect photographs of the rock slope daily controlled by a Raspberry Pi computer using the open-source library gPhoto2. Photographs are automatically uploaded to a server using 3G network for processing. This system was implemented at Castellfollit de la Roca village (Girona province, Spain), which sits on a basaltic cliff that has shown significant rockfall intensity in recent years. The 3D models obtained will allow monitoring rockfalls frequency, premonitory displacements, and calculate the erosion rate of the slope. All technical decisions taken for the design and implementation on this specific site are discussed and first results shown.This work has been carried within the framework of the research project Georisk “Avances en el análisis de la cuantificación del riesgo (QRA) por desprendimientos rocosos”, PID2019-103974RB-I00 funded by MCIN/AEI/ 10.13039/501100011033. We want to acknowledge the ICGC team for their recommendations during the design of the system and during its implementation on the field. Also, to Vilarrasa S.L enterprise for allowing the placement of the cameras on its buildings. Finally, we appreciate all help provided by the Montagut i Oix local council.Postprint (published version

Simulación de desprendimientos rocosos con fragmentación mediante RockGIS

La fragmentación en desprendimientos rocosos es un fenómeno complejo y poco comprendido que afecta a la evaluación del peligro y del riesgo. Sólo algunos modelos de simulación de caídas de rocas lo consideran explícitamente. RockGIS es un programa de simulación numérica de desprendimientos rocosos que considera la fragmentación, empleando una aproximación puntual de la masa y un modelo de rebote mediante coeficientes de restitución. Su principal innovación es la implementación del modelo de fragmentación fractal (Rockfall Fractal Fragmentation Model, RFFM) para distribuir la masa al romper los bloques. Los parámetros del modelo de fragmentación se calculan según las condiciones cinemáticas de cada impacto para reproducir diferentes escenarios de fragmentación. El funcionamiento de RockGIS ha sido verificado y validado mediante ensayos a escala real y en diversos desprendimientos rocosos naturales. En esta contribución presentamos la evolución de RockGIS en los últimos años y su aplicación a diversos casos de estudio.Este estudio ha sido desarrollado en el marco del Proyecto de Investigación “Caracterización y modelado de desprendimientos de rocas” con el acrónimo RockModels, financiado por el Ministerio de Economía y Competitividad de España, y cofinanciado por la Agencia Estatal de Investigación (AEI) y el Fondo Europeo de Desarrollo Regional (FEDER) sobre el marco del Plan Estatal de Investigación Científico-Técnica e Innovación con código de referencia BIA2016-75668-P (AEI/FEDER,UE) y el proyecto de investigación “Avances en el análisis cuantitativo del riesgo de caída de rocas (QRA) incorporando desarrollos en geomática (GeoRisk)” con referencia PID2019-103974RB-I00, financiado por MCIN/AEI/10.13039/501100 011033, Ministerio de Ciencia e Innovación (MCIN) y la Agencia Estatal de Investigación (AEI).Postprint (published version

Capturing rockfall kinematic and fragmentation parameters using high-speed camera system

This paper presents a procedure for tracking rockfall trajectories and extracting kinematic parameters from both the impacts and the resultant fragments. A set of full scale rockfall experiments was performed in a quarry located in Vallirana, Barcelona (Spain). The study site was chosen due to the presence of a rigid discontinuity surface, inclined at 42° in the middle of the slope, whose configuration was expected to favor the breakage of the blocks. The trajectories of the blocks released and of the resultant fragments were recorded with three video cameras. A C++ program was specifically developed to track the 3D trajectory of blocks and fragments, and measure velocities before and after the impact. Two different modules were implemented, one for the blocks that break and one for those that do not. The trajectory of a non-fragmented block is obtained by comparing it to its 3D model. In this way, both the center of mass position and the orientation of the block are tracked. For fragmented blocks, the local coordinates of the fragments determined from the images are converted to terrain coordinates using the program we developed. A total of 16 blocks and 36 rock fragments after impact were tracked. The parameters obtained were georeferenced and linked to a common system of 3D terrestrial coordinates. The captured parameters allow obtaining the velocity distribution of fragments, the coefficient of restitution, and energy balance for the blocks that break. To our knowledge, this is the first attempt to capture kinematic parameters of rock fragments that result from the impact and breakage of rock blocks in full-scale tests. Although the analysis of the rockfall fragmentation phenomenon is beyond of this work, we have compared the performance of the fragmented and unbroken blocks. To this purpose, we have built 3D models of the rock fragments generated using images captured with a drone. The results indicate that blocks that fragment show higher rebound velocities and coefficients of restitution than the blocks that do not although there exists a certain overlap between the two groups. Despite the experiment is carried out on the same discontinuity surface and with small variations in the impact velocities, impact kinetic energies and impact angles, the coefficients of restitution obtained present a wide range of values, both for the blocks that break and for those who do not. The number of tested blocks is too small to draw generalizable conclusions, but they highlight the stochastic nature of the rebound process and the necessity to consider additional parameters for its understanding. Finally, the results confirm the relation between the dissipated energy and, especially the impact energy and the new area created by fragmentation. Furthermore, the blocks that hit the ground with the face are those that generate the most new area while those that hit the vertex generate less.Peer ReviewedPostprint (published version

Molecular detection of hemoprotozoa and Rickettsia species in arthropods collected from wild animals in the Burgos Province, Spain

Limited information on the presence of bacterial and hematozoan infections in parasitic arthropods from Spain is available. In an attempt to address this issue, the prevalence of Theileria, Babesia, Hepatozoon, and Rickettsia species was investigated by polymerase chain reaction plus sequencing. In a survey for zoonotic pathogens in ectoparasites, 42 wild animals (which included rodents, carnivores, Sciuridae, and Cervidae) were captured in Burgos (Spain). A total of 256 arthropods (including 107 ticks, 76 fleas, and 73 mites) were collected from these mammals. Molecular diagnostic results showed that (i) Rickettsia felis was found in fleas (two Ctenocephalides felis), (ii) Hepatozoon sp. infected some fleas (two Ctenophtalmus sp. and a DNA pool of Ceratophyllus sciurorum) and Acari (one Neotrombicula sp.), and (iii) Theileria annae was found in Ixodes ricinus and I. hexagonus (each a single infected specimen). All microorganisms and parasites were genetically identical to pathogens already described in Spain or elsewhere. Infected arthropods were recovered from beech marten, bank vole, squirrel, wood mouse, and red fox. Our findings emphasize the potential risk for transmission of rickettsias to humans (namely, R. felis) in Burgos, since C. felis is capable to seek out humans for feeding. No hemoprotozoa with proven significance as human pathogens were found in the survey. However, finding T. annae in ticks recovered from wild canids suggests possible links of sylvatic and domestic cycles for some Piroplasmida

RockGIS: a GIS-based model for the analysis of fragmentation in rockfalls

A rockfall is a mass instability event frequently observed in road cuts, open pit mines and quarries, steep slopes and cliffs. After its detachment, the rock mass may disaggregate and break due to the impact with the ground surface, thus producing new rock fragments. The consideration of the fragmentation of the rockfall mass is critical for the calculation of the trajectories of the blocks and the impact energies and for the assessment of the potential damage and the design of protective structures. In this paper, we present RockGIS, a GIS-based tool that simulates stochastically the fragmentation of the rockfall, based on a lumped mass approach. In RockGIS, the fragmentation is triggered by the disaggregation of the detached rock mass through the pre-existing discontinuities just before the impact with the ground. An energy threshold is defined in order to determine whether the impacting blocks break or not. The distribution of the initial mass between a set of newly generated rock fragments is carried out stochastically following a power law. The trajectories of the new rock fragments are distributed within a cone. The fragmentation model has been calibrated and tested with a 10,000 m3 rockfall that took place in 2011 near Vilanova de Banat, Eastern Pyrenees, Spain.Peer ReviewedPostprint (author's final draft

Modelización de desprendimientos rocosos considerando la fragmentación

Determinar el riesgo al que está expuesto un edificio o una infraestructura debido a los desprendimientos rocosos mediante la Evaluación Cuantitativa de Riesgo requiere estudiar la peligrosidad, que integra la magnitud del fenómeno y la probabilidad de ocurrencia. Hoy en día la mayoría de metodologías disponibles para realizar estudios de peligrosidad no consideran la fragmentación de los bloques durante su propagación por la ladera. Este proceso tiene implicaciones directas en el estudio de la peligrosidad ya que se pueden incrementar el número de fragmentos y las energías cinéticas de los bloques disminuyen al reducirse su tamaño. En esta contribución se presenta el diseño e implementación de un módulo de fragmentación en un programa de simulación de desprendimientos rocosos llamado RockGIS y su aplicación a un caso de estudio.Postprint (published version

Rockfall fragmentation analysis: Vilanova de Banat case study

Fragmentation is a critical mechanism for the calculation of the trajectories of the blocks and the impact energies, for the assessment of the potential damage and for the design of protec-tive structures, although few rockfall models account for it. In this contribution we present an application of the trajectory simulation tool RockGIS, which explicitly accounts for fragmen-tation, to a recent rockfall event occurred near Vilanova de Banat (Spain). All parameters of the model controlling the kinematics of the propagation and fragmentation have been calibrat-ed in order to reproduce the number of fragments generated and trajectories followed by the blocks. Several performance criteria have been considered and simulations with and without accounting for fragmentation have been performed to assess their influence. The results con-sidering fragmentation show a reasonable matching with the observations in the field.Postprint (published version