INTERFEROMETRIA RADAR E MODELLAZIONE FDEM PER LO STUDIO DI FRANE IN ROCCIA: UN ESEMPIO DI APPLICAZIONE

Nella presente nota verrà illustrato un esempio di applicazione della tecnica interferometrica radar da terra (GBInSAR) e di modelli numerici avanzati di tipo combinato elementi finiti-elementi distinti (FDEM) per lo studio del cinematismo e della propagazione di una frana in roccia nell'Appennino umbro (Torgiovannetto di Assisi -PG). Con riferimento al caso di studio saranno mostrati i risultati del monitoraggio radar che hanno consentito di delimitare l'area interessata dagli spostamenti e di individuare nel cuneo in frana spostamenti differenziali non noti precedentemente. Al contempo saranno mostrati i risultati dell'analisi di scenario effettuata tramite i modelli numerici FDEM che, opportunamente tarati, hanno consentito di ricostruire i meccanismi di innesco, la possibile evoluzione e la distanza di propagazione dei fenomeni oggetto di studi

Monitoring geotechnical structures by ground based radar interferometry

This paper describes two novel remote sensing techniques based on radar sensors, respectively the Synthetic Aperture Radar (SAR) and the Real Aperture Radar (RAR), and some applications to relevant geotechnical problems with the aim to demonstrate the outcomes these types of sensors can provide. The case studies here described show how the SAR technique can provide useful information to interpret landslides’ kinematics and how the RAR can be used to monitor dam displacements and tunnels’ convergences

INTERFEROMETRIA RADAR E MODELLAZIONE FDEM PER LO STUDIO DI FRANE IN ROCCIA: UN ESEMPIO DI APPLICAZIONE

Nella presente nota verrà illustrato un esempio di applicazione della tecnica interferometrica radar da terra (GBInSAR) e di modelli numerici avanzati di tipo combinato elementi finiti-elementi distinti (FDEM) per lo studio del cinematismo e della propagazione di una frana in roccia nell’Appennino umbro (Torgiovannetto di Assisi –PG). Con riferimento al caso di studio saranno mostrati i risultati del monitoraggio radar che hanno consentito di delimitare l’area interessata dagli spostamenti e di individuare nel cuneo in frana spostamenti differenziali non noti precedentemente. Al contempo saranno mostrati i risultati dell’analisi di scenario effettuata tramite i modelli numerici FDEM che, opportunamente tarati, hanno consentito di ricostruire i meccanismi di innesco, la possibile evoluzione e la distanza di propagazione dei fenomeni oggetto di studio

Early warning monitoring of natural and engineered slopes with Ground-Based Synthetic Aperture Radar

The first application of ground-based interferometric synthetic-aperture radar (GBInSAR) for slope monitoring dates back 13 years. Today, GBInSAR is used internationally as a leading-edge tool for near-real-time monitoring of surface slope movements in landslides and open pit mines. The success of the technology relies mainly on its ability to measure slope movements rapidly with sub- millimetric accuracy over wide areas and in almost any weather conditions. In recent years, GBInSAR has experienced significant improvements, due to the development of more advanced radar techniques in terms of both data processing and sensor performance. These improvements have led to widespread diffusion of the technology for early warning monitoring of slopes in both civil and mining applications. The main technical features of modern SAR technology for slope monitoring are discussed in this paper. A comparative analysis with other monitoring technologies is also presented along with some recent examples of successful slope monitorin

Thermal performance of a metro station in Turin equipped with energy geostructures

High pollution levels combined with the lack of green spaces are hitting many cities leading to the exploitation of the underground for transportation. Given the need to foster local energy sources with low environmental impact, energy geostructures are more and more being explored. In this context, the promising outcomes of the experimental campaign on the thermal activation of tunnel segments carried out on Turin ML1 South Extension encouraged the authors to investigate applicability of energy geostructures for Turin ML2 project. This paper is intended to focus on the understanding of the thermo-hydraulic behaviour of a metro station equipped with energy diaphragm walls. A 3D FE numerical model reproducing the layout of the planned Mole-Giardini Reali station is used to study the energy exchange potential of the thermoactive walls. The quantification of the exploitable energy to meet the user demands of the station and of buildings above will be discussed on the basis of the results obtained

Combined Finite–Discrete Numerical Modeling of Runout of the Torgiovannetto di Assisi Rockslide in Central Italy

The combined finite–discrete-element method (FDEM) is an advanced and relatively new numerical modeling technique that combines the features of the FEM with those of the discrete-element method. It simulates the transition of brittle geomaterials from continua to discontinua through fracture growth, coalescence, and propagation. With FDEM, it is possible to simulate landslides from triggering to runout and carry out landslide scenario analyses, the results of which can be successively adopted for cost-effective early warning systems. The purpose of this paper is to describe the results of the FDEM simulations of the triggering mechanism and the evolution scenarios of the Torgiovannetto di Assisi rockslide (central Italy), a depleted limestone quarry face where a rock wedge with an approximate volume of 182,000 m3 lies in limit equilibrium conditions, posing relevant issues in terms of civil protection. The results obtained demonstrate that the FDEM is able to realistically simulate the different phases of such a complex slope’s failure as well as to estimate both its runout distances and velocity, key features for landslide risk assessment, and management

Remote monitoring of the Comba Citrin landslide using discontinuous GBInSAR campaigns

This paper describes the use of the discontinuous Ground-Based Interferometric Synthetic Aperture Radar technique (GBInSAR) to monitor the displacement of the Comba Citrin landslide in the North Western Italian Alps. Two GBInSAR surveys were carried out respectively during the summer and the fall of 2015 separated by a temporal baseline of 63 days. For each GBInSAR survey, which lasted respectively 166.2 h (6 dd, 22 h, 12′) and 238.3 h (9 dd, 22 h, 18′), two sets of 139 and 275 SAR images were acquired. After the selection of a specific stack of Persistent Scatterers, the SAR images of each survey were analyzed separately and in combination with the images of the other survey to detect the possible displacements occurred both in every single survey as well as in the elapsed time between the two different campaigns. The displacement maps showed that two different sectors of the monitored slope were affected by millimetres to centimetres movements during the monitoring period. The results obtained for the Comba Citrin landslide show that the discontinuous GBInSAR can be reliably adopted to monitor the displacement of landslides moving at an average rate of few centimetres per year

Early-warning debris flow and avalanches detection system based on optical fiber polarization sensing

Landslides, avalanches and debris flows are the main hazards in the mountain environment, endangering people and infrastructures. The existing monitoring systems in the geotechnical field are often unsuitable for real-time applications, such as early-warnings of the aforementioned events. We present an optical fiber system able to give an alarm when some anomalous event is detected. Experiments have been carried on a reduced scale model of a slope of a mountain, showing that state of polarization monitoring is a reliable way to early-detect anomalous vibrations

A new real-time debris flow and avalanches detection system based on optical fiber sensing

The real-time detection of potentially destructive water, earth and snow mixtures such as debris flow and avalanches is a topic of growing interest to mitigate the risk in anthropized areas such as the Alpine region. In view of this, a new cutting-edge debris flow and avalanche detection system, called OPTIALP, was developed. The proposed system exploits the polarization variations induced on the fiber by mechanical vibrations, for the automatic detection along their propagation path of potentially destructive snow and soil-water mixtures. One of the main values-add of the OPTIALP system is the “quasi distributed” and spatially continuous detection along the whole fiber which improves the current monitoring technologies relying on “discrete” monitoring points and sensors. The OPTIALP system was designed and thoroughly tested in the laboratory environment by means of a specific setup. Over 650 tests were carried out and a new signal processing algorithm developed in Matlab environment capable to interpret the data acquired was created. The results showed that the OPTIALP system is able to correctly identify the signals produced by lab-scale mass movements