117 research outputs found
Development of a geological model useful for the study of the natural hazards in urban environments. An example from the eastern sector of Rome (Italy)
Detailed knowledge of the subsoil setting is an extremely important issue for a correct risk reduction policy, especially when dealing with urban areas hosting cultural heritage, which enhance risk conditions even at low geo-hazard levels, as in the case of Rome. In general, the reliability of risk assessments related to geo-hazards is strictly dependent on the resolution of the reference geological model. The study presented here exemplifies an integrated methodology aimed at refining the knowledge of the geological setting in unique urban environments, such as the city of Rome, where canonical approaches are limited by the scarcity of outcrops and ad-hoc geognostic surveys may be expensive and time-consuming. The methodology used in the study is based on a critical review of available geological, stratigraphic, archeological and historical-archival data. The integration of such data, properly stored, managed and analysed in a GIS environment, made it possible to: i) better frame the geological setting of a wide sector of the eastern part of Rome; and, in particular, ii) focus on buried natural morphologies (i.e. valleys) strongly modified by progressive urbanisation that determined their filling with huge thickness of backfills, which often represent a critical geotechnical issue. A detailed geological model was thus developed. The model shows slight but significant differences with respect to already available official maps, emphasising the need for carrying out in-depth analyses of already existing data from different sources, in order to collect thematic data to be used for effective land management policies
Recorded displacements in a landslide slope due to regional and teleseismic earthquakes
Regional and teleseismic earthquakes can induce displacements along joints in a landslideinvolved
rocky slope in Central Italy. The rarity of these effects is due to specific physical
properties of the seismic signals associated with: (i) the energy content, (ii) the distribution of
relative energy and peak of ground acceleration related to the ground motion components and
(iii) the spectral amplitude distribution in the frequency domain; these properties allow the
triggering earthquakes to be distinguished from the others. The observed effects are relevant
when compared to the direction of the landslide movement and the dimensions of the involved
rock mass volume. The landslide movement is less constrained in the direction parallel to the
dip of the slope and the landslide dimensions are associated with characteristic periods that
control the landslide deformational response in relation to the spectral content of the ground
motion. The earthquake-induced displacements are significant because they have the same
order of magnitude as the average annual cumulative displacement based on a decade of strain
measurements within the slope
Supporting Tunnelling Excavation of an Unstable Slope by Long Term Displacement Monitoring
A complex multi-sensor monitoring platform for the continuous control of an unstable slope affected by tunneling excavation, was realized between 2007 and 2008 after the first collapse of an already built tunnel entrance. The monitoring system was made of some inclinometric and piezometric sensors up to 70 m deep, a topographic system, a Terrestrial SAR Interferometer, a weather station, a photocamera and some load cells installed on bulkheads anchors. The continuous monitoring of the slope during different working phases (planning of stabilization works, realization of stabilizations works and tunneling excavation) allowed us to continuously control the slope behaviour, thus guaranteeing the operations in safety conditions. Data derived from the displacement monitoring, combined with geological and geomechanical information, allowed us to better define the complex engineering geological model of the slope, thus supporting the design of stabilization works. Furthermore, the real time control by TInSAR allowed us to stop the excavations of the tunnel for three times following the sudden increase of the slope displacement velocity. Stability thresholds of velocity and displacement have been also defined using semi-empirical models on the basis of the collected historical displacement data
Comparison of approaches for data analysis of multi-parametric monitoring systems. Insights from the Acuto test-site (Central Italy)
This paper deals with monitoring systems to manage the risk due to fast slope failures
that involve rock masses, in which important elements (such as infrastructures or cultural heritages,
among the others) are exposed. Three different approaches for data analysis were here compared
to evaluate their suitability for detecting mutual relations among destabilising factors, acting on
different time windows, and induced strain effects on rock masses: (i) an observation-based approach
(OBA), (ii) a statistics-based approach (SBA) and (iii) a semi-empirical approach (SEA). For these
purposes, a test-site has been realised in an abandoned quarry in Central Italy by installing a
multi-parametric monitoring sensor network on a rock wall able to record strain effects induced by
natural and anthropic forcing actions (like as temperature, rainfall, wind and anthropic vibrations).
The comparison points out that the considered approaches allow one to identify forcing actions,
responsible for the strain effects on the rock mass over several time windows, regarding a specific
size (i.e., rock block dimensional scale). The OBA was more suitable for computing the relations over
short- to medium time windows, as well as the role of impulsive actions (i.e., hourly to seasonal
and/or instantaneous). The SBA was suitable for computing the relations over medium- to long time
windows (i.e., daily to seasonal), also returning the time lag between forcing actions and induced
strains using the cross-correlation statistical function. Last, the SEA was highly suitable for detecting
irreversible strain effects over long- to very long-time windows (i.e., plurennial)
Terremoti e attività antropiche
Volume didattic
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