Riviste Online SApienza - R.O.SA - 2 (Sapienza University of Rome)
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Determining the Rock Brittle Index (BI) using multivariate regression (a case study)
Get PDFOne of the geotechnical properties of rocks, which is particularly important in sensitive projects such as oil and gas extraction, nuclear waste disposal, and underground drilling, is their brittleness. Currently, here are no standards methods for direct measurement of rock brittleness. Different studies have used various indirect methods to predict rock brittleness index (BI). However, researchers have paid less attention to the prediction of BI using multivariate regression. Accordingly, this research has used the multivariate regression method to determine BI considering mechanical characteristics. Specifically, we sed uniaxial compressive strength (UCS), modulus of elasticity (E), pressure wave velocity (Vp), and shear wave velocity (Vs), and physical characteristics, including porosity (n) and density (ρ) to determine the BI. Statistical indicators, R square, results of ANOVA (Analysis of Variance) test, coefficients, beta statistics, and VIF were used in the first step to evaluate the regression relationships. Then, residual nalysis of each regression were performed. Finally, the correlation between the calculated and predicted BI values was investigated using each regression. The best results were obtained using UCS and E or UCS and Vs in the bivariate regression and UCS, E, and Vs in the three-variable regression. According to the results, increasing the number of variables in multivariate regressions leads to more accurate predictions of BI
New records and interesting data for the Sardinian spider fauna (Arachnida: Araneae)
Get PDFWe present new distributional data of 24 spider species in Sardinia, including 7 endemic and 1 poorly recorded species. Sixteen species from 7 families and six species from 2 families are recorded for the first time in Sardinia and Italy, respectively. Among these, the reported presence of Cepheia longiseta and five other species allows us to include the Synaphridae family and five genera (Anagraphis, Hahnia, Minyriolus, Thaumatoncus, Trabea) in the Sardinian spider checklist, and two genera (Anagraphis and Thaumatoncus) in the Italian spider checklist. Relevant faunistic and distribution notes of poorly collected species are also provided
Chronology of the worldwide spread of a parthenogenetic beetle, Reesa vespulae (Milliron, 1939) (Coleoptera: Dermestidae)
Get PDFReesa vespulae (Milliron, 1939) is a parthenogenetic synanthropic subcosmopolitan dermestid pest native to the Nearctic region. The chronology (1942–2020) of its spread outside its native range, its general distribution and ecology are summarized and discussed. Its spread is likely to be the result of multiple introductions into the different zoogeographic regions, and secondary translocations therein; the oldest records from outside its native range are: 1942 (Australian region), 1946 (Neotropical region), 1957–1958 (Palaearctic region) and 1986–2010 (Oriental region). Reesa vespulae is excluded from the Afrotropical fauna, since the sole available record was based on a misidentification, while it is recorded from central Italy for the first time, moreover its oldest Algerian and Austrian records are provided. The need for preventive measures against dermestid infestations in natural history collections is highlighted
Groundwater asbestos pollution from naturally occurring asbestos (NOA): a preliminary study on the Lazio valleys and Balangero plain area, NW Italy
Get PDFGroundwater or surface water flow into natural rock formations containing asbestos (NOA), e.g. serpentinites and metabasites, may result in water asbestos pollution. In fact, asbestos-bearing rocks weathering is the principal natural cause of fibres water-dispersion. As asbestos constitute a risk to human health, it is crucial, into NOA contexts, to verify the occurrence of mineral fibres in water resources, given their importance for agricultural and industrial activities and as a primary source for drinking water. For this purpose, the Lanzo Valleys and Balangero Plain (NW Italy) were selected as study area where to evaluate the possible occurrence of asbestos in groundwater, to correlate it to the geolithological and hydrogeological characteristics of the context and therefore to evaluate the possible mobility of asbestos in aquifers. The results of this preliminary study show the presence of asbestos in groundwater, generally occurring in very thin fibres which require TEM-EDS analysis. Water chemical characters, particularly dissolved cations, reflect the lithologies which occur in the area; concerning trace metals, only Ni shows a relation with NOA occurrence. In addition, several problems on sampling and analysis procedures are highlighted and discussed
Micropiles tripods shields (MTS) as unconventional breakers for the control of moderately rapid earthflows (Sassi Neri landslide, Northern Apennines)
Get PDFThe paper deals with the idea, design and implementation of unconventional one-of-a-kind Micropiles Tripods Shields (MTS) intended to break and decelerate moderately rapid earthflows surges in the track zone of the Sassi Neri landslide (Nure Valley, Northern Apennines, Province of Piacenza, Italy). The MTS are inspired to floating anchors and “chevaux de fries” used in wartime. The basic elements are tripods of 193 mm diameter steel micropiles laid out at triangle, driven into the stable bedrock and emerging some meters aboveground. Each tripod consists of a vertical upslope central pile and two lateral oblique piles, linked by two transversal beams and connection plates aboveground. Multiple tripods are spaced along transversal rows to form Micropiles Tripods Shields (MTS) to advancing earthflows. The design of MTS has been based on field investigations such as boreholes and geophysics, that indicated a limited thickness of landslide deposits in the track zone where MTS have been installed. The forces resulting from active earthflows fronts have been estimated both with geotechnical and hydraulic computations. The analysis of vertical and transversal forces as well as bending moments acting on a single tripod versus the characteristic resistances was carried out using a bi-dimensional scheme with finite-elements software Plaxis, that indicated that the stress levels were compatible with the structural resistance of the tripods. The construction of MTS took place in 2018, involving working site preparation with partial lime-treatment of the surficial layers, underground micropiles drilling and installation, aboveground micropiles welding, tripods completion with connection beams and plates. Some tripods have been instrumented with load cells for monitoring earth pressures against micropiles, electric transducers for groundwater monitoring next to the piles, tiltmeters for tripods rotations and a total station for slope and tripods movements monitoring. Results show that the acceleration of slope movements corresponds to a generalized increase of pore water pressure at all the monitored tripods and to temporary slight tilting of the tripods which has so far being fully recovered when the landside slowed down and pressure decreased. This pioneering application indicates that once the characteristics of the earthflows are carefully considered, the depth to the bedrock in the installation zone is limited, and the logistical conditions in the field during construction are adequate, the MTS can be taken into consideration as a possible unconventional solution to break down and control moderately rapid earthflows
An Alternative to commercial optical fibre sensors for shallow ladslide monitoring – interferometric optical fibre sensing
Get PDFOptical fibre-based monitoring has settled in the field of geohazards monitoring. Interferometric optical fibre sensors are the least used in landslide monitoring, while classical approaches rely on Fibre Bragg Grating and Brillouin Optical Time Domain Reflectometry/Analysis. Landslide monitoring goes hand by hand with the development of technology. While authors tend to focus on the unprecedented accuracy and reduced costs of the sensor itself, the economic and practical aspects related to the interrogating systems are often disregarded. Recently, a simpler and significantly more cost-effective approach has been introduced through “integral coherent measurements” because they yield an integral of the signal response over the entire length of the optical fibre sensor. This sensing system proves to be suitable to provide an overall indication of the state of the entire monitored domain and yield indications of the onset of motion with a high temporal resolution. The sensor has been tested in controlled conditions as a monitoring tool in a downscaled landslide model. We exploit the large bandwidth and high frequency of acquisition in order to detect high frequency elastic waves. The proposed sensor is able to distinguish the vibration footprint generated by ground movement. The results obtained from the experimental tests demonstrate that the proposed sensing system is able to recognize the onset of motion some minutes before a visual indication of instability could be observed
A Combined GNSS-DINSAR-IRT study for the characterization of a deep-seated gravitational slope deformation
Get PDFLarge deep-seated gravitational slope deformation (DsGSD) are slope instability phenomena affecting high relief-energy hillslopes and characterized by a high degree of complexity, enhanced also by wideness of the affected area and lithological heterogeneity. A combined approach based on different remote survey methodologies is herein presented with the aim of characterizing one of the most relevant DsGSDs in Sicily (Italy). The Scopello landslide involves the external margin of an overthrust plane, where a rigid carbonate tectonic unit overlies a ductile clayey substratum. The evidence of structural discontinuities crossing the rock masses and of unstable rock mass portions were pointed out by IRT, whose results were combined with the analysis of morphological features retrieved from a DTM, highlighting the presence of regional systems controlling the rock fracturing. Three GNSS surveys have been carried out in 2004 and 2005 on a 27-vertex geodetic network, attesting up to 20cm deformations caused by the triggering of landslides in the substratum. DInSAR results, obtained from the processing and interpretation of ENVISAT and Cosmo-SkyMed images, both in ascending and descending geometry for the time span 2002-2018, allowed evaluating the displacement rates over the area, highlighting that the movement is still active in its upper sector
Can\u27t tell a book by its cover: disjointed groundwater contamination and land use in an alluvial aquifer of Northern Italy
No full textIn the Po plain, intensive agriculture is supported by large irrigation volumes and use of fertilizers. We analysed the effects of different land uses in a sector of the Mincio River on groundwater hydrochemical characteristics and hypothesized local regulation of NO3- contamination. In the unconfined coarse-grained alluvial aquifer, hydraulic heads were measured monthly in 17 wells from May 2019 to December 2019, to trace how the aquifer recharge and manure spreading influence groundwater physico-chemical parameters and quantity. The experimental site was divided into two different zones on the left and right bank characterized by different land use. Although these dissimilarities concern different irrigation and fertilization practices, we measured in both areas nitrate (NO3-) contamination in groundwater, with concentrations exceeding legislative limits by a factor of 2. Our results suggest that NO3- contamination in this area is not only driven by specific land use and related agricultural practice; rather, other local factors intrinsic to the local aquifer and groundwater characteristics play an important role. Presented results on groundwater quality and quantity provide useful information to increase knowledge on local N dynamics and to the administrations regulating fertilizer use in this area, already reported as Nitrate Vulnerable Zones (NVZ)
Spatiotemporal data management of recurrent debris flow events using object-oriented data modelling
Get PDFThis work is focused on the study of recurrent debris flow events on the north-facing mountain slope of the Bulgheria massif (Cilento Unesco Geopark, southern Italy). These phenomena pose a threat for at least two villages and infrastructures on the lower slope. The main morpho-structure of the mountain slope is strongly controlled by the tectonic overlapping in form of multiple thrust-folding of the Meso-Cenozoic limestone related to the inner margin of the Apennine Carbonate Platform over lower-middle Miocene marly-clay flysch and previously overthrusted basinal units ranging from upper Oligocene to lower Miocene. Therefore, the mountain slope is sculpted by erosional deep incided ravines and sub-structural interfluve cliffed slopes passing downslope to depositional piedmont by evident and abrupt knick-point. Channels along the slope are periodically filled both through rock fall deposits occurring on channel’s flanks and by soil creep and sheet wash phenomena at channel’s heads, which supply new material for future flows. Such relationship between infilling rock fall phenomena and debris flows represents an interesting case study of interaction among different and concurrent landslide types providing an optimal example of space-time evolving landslide system. Landslide classes have been stored and mapped using a previously proposed object-oriented and event-based model and producing in this way a multi-temporal database. Landslide objects have been grouped into landslide subclasses using the latest landslide classification available. In the next step, a hierarchical classification has been applied, introducing two levels of aggregation and one level of decomposition. Landslide complexes group landslide objects of the same class sharing spatial connection, defining rock fall complex objects and granular soil wet flow complex objects. Landslide systems group all the interacting landslides, regardless of their type. Landslide components describe the various portions of a single landslide object. Every stored object has its temporal attributes distinguishing between time points (events) and time intervals (time frames). The integration of complex spatial relations through topological analysis and temporal characterization of data allows to build a flexible database structure adaptable to several specific needs and different outputs, such as basic landslide maps or event maps, multi-temporal and frequency analyses, or the study of the interactions among different types of landslide hazards. In this framework, a neologism could be introduced in landslide studies, as landslide eventory mapping, as a challenge for future applications
The leaf-mining flies of the family Agromyzidae of the Maltese Islands are revisited and updated with new data and records (Diptera: Brachycera, Acalyptrata)
Get PDFThe Agromyzidae of Malta is reviewed and all 81 species are listed with additional data. Three genera are reported for the first time: Japanagromyza Sasakawa, Aulagromyza Enderlein and Phytoliriomyza Hendel. Two species in the genus Aulagromyza Enderlein and one in Phytomyza Fallén cannot be named at present. The commonest species on the islands, the pest species and 37 new records are indicated. The phenology of the species belonging to this family as applies to the Maltese Islands is tabulated and discussed