The rockfall process is one of the most relevant problem affecting some areas and roads located in the Apennines part of Umbria (central Italy). Such study considers some sections of road “SS 685 - Tre Valli Umbre” between Piedipaterno and Biselli in Valnerina (River Nera Valley) and the road “SS 73 bis - Bocca Trabaria” in the portion close to the mountain pass. In fact in these areas the geomorphological assessment is characterized by very step slopes where limestone and arenaceous-calcarenitic rocks outcrop, stratified and deeply fractured; this situation promotes high energy landslides and, in particular, rockfalls phenomena. Rockfall's frequency and intensity are related both to the weather conditions of mountainous areas, and to the seismic events (in particular in Valnerina), similar to those have historically affected Eastern Umbria. The geostructural and geomechanical surveys have been performed both by traditional methods and by using a ground laser scanner device (model LMS-Z420i, produced by Riegl Laser Instrument Systems). In order to perform the geomechanical characterization of materials involved in the rockfall, some field surveys and laboratory tests on opportunely shaped samples were carried out. The measured volumetric weight of limestone is 25,8–26 kN/m3 and the uniaxial compressive strength is 80 – 82 Mpa. The investigation of the tension-deformative conditions of the rock slopes along the Valnerina and the Bocca Trabaria roads were carried out by numerical simulations using the UDEC code, particularly useful to solve problems regarding fractured rocks. The distinct element approach (that UDEC adopts) is in fact used for studies of rock mechanics and specifically for the stability of rock slopes. UDEC is able to analyse the behaviour of discontinuous systems and to investigate complex failure mechanisms. The numerical code allows also to simulate the effects of external factors, such as earthquakes, so important for the evaluation of Valnerina slope's stability.
Risk scenarios for roads along slopes affected by rock avalanches and falls in some sample cases in Umbria (central Italy)
CENCETTI, Corrado;CONVERSINI, Pietro;DE ROSA, PIERLUIGI;FREDDUZZI, ANDREA;MINELLI, ANNALISA;
2013
Abstract
The rockfall process is one of the most relevant problem affecting some areas and roads located in the Apennines part of Umbria (central Italy). Such study considers some sections of road “SS 685 - Tre Valli Umbre” between Piedipaterno and Biselli in Valnerina (River Nera Valley) and the road “SS 73 bis - Bocca Trabaria” in the portion close to the mountain pass. In fact in these areas the geomorphological assessment is characterized by very step slopes where limestone and arenaceous-calcarenitic rocks outcrop, stratified and deeply fractured; this situation promotes high energy landslides and, in particular, rockfalls phenomena. Rockfall's frequency and intensity are related both to the weather conditions of mountainous areas, and to the seismic events (in particular in Valnerina), similar to those have historically affected Eastern Umbria. The geostructural and geomechanical surveys have been performed both by traditional methods and by using a ground laser scanner device (model LMS-Z420i, produced by Riegl Laser Instrument Systems). In order to perform the geomechanical characterization of materials involved in the rockfall, some field surveys and laboratory tests on opportunely shaped samples were carried out. The measured volumetric weight of limestone is 25,8–26 kN/m3 and the uniaxial compressive strength is 80 – 82 Mpa. The investigation of the tension-deformative conditions of the rock slopes along the Valnerina and the Bocca Trabaria roads were carried out by numerical simulations using the UDEC code, particularly useful to solve problems regarding fractured rocks. The distinct element approach (that UDEC adopts) is in fact used for studies of rock mechanics and specifically for the stability of rock slopes. UDEC is able to analyse the behaviour of discontinuous systems and to investigate complex failure mechanisms. The numerical code allows also to simulate the effects of external factors, such as earthquakes, so important for the evaluation of Valnerina slope's stability.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
