The Missouri Rock Fall Hazard Rating System (MORFH RS) was recently developed for the State of Missouri. It is a system that separates the risk of failure from the consequences of failure factors, ...thus allowing better assessment of the hazards of rock falls. Efficiency is gained by video logging of highway rock cuts from vehicles moving at highway speeds, pre-screening of rock cuts from video images, making some of the measurements needed for the rating system on digital images, and using GPS receivers to collect field data and GIS to organize all the data. This paper describes the rationale behind the parameters selected for the system using factor analysis and other methods and the verification of the system through sensitivity studies and multiple rater tests. Simulations of remediation techniques were applied to recognize the most effective methods for remediation.
Rock fall phenomena are a major hazard during construction in mountainous regions. At the Marun Dam site, rock falls occur almost every day on the downstream side. The left flank power plant and ...access roadways as well as the right flank roadways are susceptible to rock falls from the 100 m high cliffs with slopes of 70–90°. The cause is a combination of the orientation of the bedding planes and joint sets and the active tectonic setting of the area. The paper reports the use of RocFall and Dips software to simulate the conditions in order to define the potential risk of rock falls at the Marun Dam site, which could affect workers as well as structures. In the light of the Falling Rock Hazard Index obtained, preventative and remedial measures are suggested.
The Pietra di Bismantova, a vast biocalcarenite slab, is an impressive landmark and a unique feature in the gentle hilly landscape of the Reggio Emilia Apennines, Italy. It consists of a stratified ...calcareous rock type, rich in molluscs and other fossilised remains typical of a tropical climate. The site also has significant historical and cultural interests, including remains from Bronze Age and early Iron Age settlements. The perpendicular rock faces of the Pietra di Bismantova have for many years attracted rock climbers and hikers. Furthermore, the sheer calcareous walls are favoured sites for endemic plants and nesting of rare birds. Since the end of the last glaciation, the site has been subject to intense degradational processes affecting the rock slopes. Today, these pose serious problems for its conservation and the safety of visitors. The southern part is mainly affected by occasional rockfalls of varying magnitude. In contrast, the north-eastern part is much more jointed and dismembered and is subdivided into several loose blocks subject to slope movements with a complex style of activity. The results of a geomechanical and geomorphological survey are used to identify the area most prone to geomorphological hazards, particularly rockfalls. They show that the areas potentially most subject to landslides are the SE, NE and NW faces, where the rock parameters are poorest and degradational processes are particularly intense. Numerical modelling of rockfall phenomena indicates that the hazards are particularly high along the SE and W faces, where footpaths and climbing tracks are also located. Remedial measures should be introduced in these critical areas to stabilise the cliff and guarantee safe access for the numerous visitors to this geosite.
The road network within the state of Missouri is contained within a diverse suite of terrains, which in some areas presents substantial rock fall and slope stability hazards. Highway rock cuts must ...be maintained for the safety of the motoring public. Since highways cover vast areas through differing geological terrains, it is not cost effective to remediate all rock cuts; remediation efforts have to be prioritized. Even doing traditional geological engineering evaluations on all the rock cuts is prohibitive. The development of the Missouri Rock Fall Hazard Rating System (MORFH RS) for Missouri rock cuts along the Missouri Highways utilized three phases. Phase I included the development of a computer program (RockSee) for screening and measurement of physical features using computer scaled video images. Digital video image of entire highways can be acquired at highway speeds. Later using a computer, engineers can review the video, select areas that look like they may be problematic, and plan further investigations at those sites. The physical features that required in the classification systems can be measured, such as slope heights, slope angles, ditch width, ditch depth, ditch volume, ditch capacity excedence, and rock fall quantity, can be measured directly on the digital images. Phase II include the development of MORFH RS, which is a new scheme for rating of rock fall hazards along the Missouri highways. This system focuses on the risk of failure and the consequence of failure. In MORFH RS, risk and consequence factors are given equal weight and isolated from each other. The ratings for the categories that relate to risk or consequence are easy to determine and are more objective. The risk-consequence rating system can be used by the DOT (Department of Transportation) to cost effectively determine the need and priority of remediation, and help facilitate the design of maintenance on rock cuts in order to provide for the safety and convenience of the motoring public by reducing the risk and consequence of falling and fallen rock to life and property. Phase III include the development of a database management system using GIS (geographic information system). This phase includes gathers rock fall data collection and building the database using GIS with using different data layers. Over 500 rock slopes were inspected using video images. A total of 300 slopes were given a detailed rating and field investigation. Following the completion of these field ratings, a GIS database was constructed for all the sites that need detailed rating and includes basic descriptions, locations, and photographs of the slope.
Une nouvelle méthode d’analyse en retour d’éboulements rocheux est présentée, qui prend en compte, de manière probabiliste, les accélérations sismiques subies par les compartiments rocheux depuis ...qu’ils sont exposés à la surface des falaise. L’accélération minimale subie dépend de la durée d’exposition du compartiment, qui est estimée à partir d’un modèle d’érosion. Deux modèles expliquant la dégradation de la stabilité au cours du temps sont utilisés pour analyser trois éboulements survenus dans des falaises calcaires : l’un fait intervenir la dissolution, l’autre la propagation instable de la fissuration. Ces modèles, calés sur des cas réels, permettent d’estimer par excès, la durée de vie de compartiments rocheux potentiellement instables.
A new method for rock fall back-analysis is proposed, which takes into account, in a probabilistic way, the seismic accelerations underwent by the rock compartments since they have been exposed at the cliff surface. The minimal underwent acceleration depends on the exposure time of the compartment, which can be estimated from an erosion model. Two models are proposed to explain the decrease of the stability with time, and they are applied to three failures occurred in limestone cliffs. The first one involves the limestone dissolution and the second one the unstable crack propagation. These models, which have been fitted with real cases, make it possible to estimate the life expectancy of potentially unstable rock compartments.
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