323,260 research outputs found
La zona dal torrente Titerno al Fiume Calore
No full textThe author presents the results of the researche in the Ager Telesinus (authorities of Faicchio, Puglianello, Amorosi, S. Salvatore Telesino e Telese Terme) for the Archaeological Map.Il contributo presenta i risultati delle indagini condotte nel territorio della città di Telesia (comuni di Faicchio, Puglianello, Amorosi, S. Salvatore Telesino e Telese Terme) per la redazione della Carta archeologica
Modelling of reinforced concrete framed structures interacting with a shallow tunnel
No full textThe construction of tunnels in urban areas inevitably entails the interaction with existing structures. Current design approaches for the evaluation of tunnelling induced damage on buildings are based on the semi-empirical evaluation of the deflection ratios and horizontal tensile strains at foundation level, assuming that the structure will conform to the greenfield displacements. If the stiffness of the structure is deemed significant, coupled numerical analyses have to be performed including a model of the building. The latter can be simulated using either an equivalent solid (e.g. Potts and Addenbrooke, 1997; Losacco et al., 2014), for which appropriate equivalence criteria have to be defined, or a detailed structural model (e.g. Burd et al., 2000; Amorosi et al., 2014; Fargnoli et al., 2015). This paper focuses on the phenomenon of soil-structure interaction due to mechanised tunnel excavation, with special reference to reinforced concrete framed buildings. The study aims at identifying those cases in which the building significantly alters the settlement trough induced by the excavation with respect to greenfield one. In such cases the relative contribution of the foundations and of the structural members to the global stiffness of the building is assessed, seeking for the optimal level of simplification of the structural model. The research is carried out by performing three-dimensional parametric finite element analyses of the problem at hand, adopting the geotechnical conditions and the tunnel characteristics of the Milan metro-line 5 (Fargnoli et al., 2015)
The role of Late Quaternary incised valley systems in coastal-plain aquifer geometry: A case study from the Arno Plain (Ligurian Sea, Italy).
No full textThe Late Quaternary subsurface successions buried beneath several delta-coastal plains exhibit distinct cyclic facies patterns
that reflect the predominant control exerted by climate-eustatic factors on sedimentation, at Milankovitch and sub-
Milankovitch scales. However, local subsidence co-operates with Late Quaternary glacio-eustatic fluctuations in determining
changes in accommodation space through time and space. During phases of sea-level rise (interglacial periods), subsidence
further increases the accommodation space. On the other hand, during the subsequent phases of sea-level fall (glacial periods) subsidence works to mitigate the accommodation space reduction, resulting in a better preservation of the
depositional record.
In the case of rapidly subsiding regions, such as the Po Plain (N Adriatic Sea, Italy), the combined tectonic-eustatic effect led
to a vertically stacked succession of transgressive-regressive (T-R) sequences forming a multilayered aquifer system (Amorosi
and Colalongo, 2005; Amorosi and Pavesi, 2010). In a hydrostratigraphic view, sheet-like, channel-belt fluvial bodies, tens of
m-thick in the regressive portion of the T-R sequences represent major aquifers. In contrast, pronounced fluvial incisions
occurred during glacial periods in coastal plains characterized by lower rates of subsidence, as those facing the Ligurian-
Tyrrhenian margin (e.g. Arno Plain, Ombrone Plain, Tiber Plain, Volturno Plain). These erosive processes led to the formation
of km-wide and tens of m-thick paleovalleys able to erode confined aquifers, reducing their lateral continuity. In these
contexts, the reconstruction of the aquifer systems is further complicated by the incised valley fill (IVF) successions formed
during the subsequent interglacial periods. These IVFs, which consist predominantly of estuarine muddy deposits, represent,
in fact, localized impermeable barrier to ground-water circulation. A high-resolution multiproxy approach (sedimentological,
faunal and chronological data) and the application of sequence stratigraphic principles can furnish a successful threedimensional
representation of such complex aquifer systems.
The Arno coastal plain (Ligurian Sea, Italy) represents an ideal setting where to investigate the hydrostratigraphic role of
incised valley systems (IVSs), as two well-preserved IVFs have been identified within the uppermost 100 meters and dated to
two non-consecutive interglacial cycles (MIS 7 and MIS 1; Amorosi et al., 2008; Rossi et al., in press). Based on a large
subsurface stratigraphic dataset, composed of hundreds of > 50 m long cores, 14C and ESR chronological data, and
stratigraphic correlation, a representation of the Arno Plain aquifer system is outlined. We focused on the identification and
mapping of potential aquitards/aquicludes (IVFs) and aquifers. These latter include: (i) laterally discontinuous gravel terrace
deposits developed at different stratigraphic levels along the paleovalleys flanks, (ii) lenticular channel-belt sand bodies
formed during the glacial phases that preceded IVSs formation, and (iii) post-valley fill coastal-marine sands showing a
landward-wedging geometry.
References
Amorosi A. and Colalongo M.L. (2005). The linkage between alluvial and coeval nearshore marine successions: evidence from
the Late Quaternary record of the Po River Plain, Italy. In: M.D. Blum, S.B. Marriott & S.F. Leclair (Eds.) Fluvial Sedimentology
VII. Int. Assoc. Sedimentol. Spec. Publ. 35, 257–275.
Amorosi A. and Pavesi M. (2010). Aquifer stratigraphy from the middle-late Pleistocene succession of the Po Basin. Mem.
Descr. Carta Geol. d’It. XC, 7–20.
Amorosi A., Sarti G., Rossi V. and Fontana V. (2008). Anatomy and sequence stratigraphy of the late Quaternary Arno valley fill
(Tuscany, Italy). In: A. Amorosi, B.U. Haq & L. Sabato (Eds.) Advances in Application of Sequence Stratigraphy in Italy.
GeoActa Spec. Publ. 1, 55–66.
Rossi V., Amorosi A., Sarti G. and Mariotti S. (in press). Late Quaternary multiple incised valley systems: an unusually wellpreserved
stratigraphic record of two interglacial valley fill successions from the Arno plain (northern Tuscany, Italy).
Sedimentology
Sequence stratigraphy of an alluvial-nearshore transition depositional system: insight from the Eocene Montserrat conglomerates of Eastern Spain
No full textSequence-stratigraphic concepts are well established within
deltaic, coastal and shallow-marine depositional systems,
whereas their application becomes increasingly difficult
landwards, where the effects of climate, tectonics
and changes in sediment supply may have been overwhelming
sea-level fluctuations. Despite severa! attempts
have been promoted in order to apply the principles of
sequence stratigraphy to non-marine (coastal-plain and
fluvial) successions, at present there is no generai acceptance
of any single model.
The Eocene Montserrat conglomerates, a well-exposed
fan-delta complex cropping out 40 km NW of Barcelona,
represent a useful case history to investigate the stratigraphic
relationships between alluvial and coeva! littoral
deposits, for a number of reasons: i) the alluvial to
nearshore transiti o n takes piace over distances of few kilometres
only; ii) spectacular outcrop exposures enable
physical correlation of major sedimentary bodies; iii) the
regional and local stratigraphic framework have been
described in detail by previous work.
The alluvial system contains eight fourth-order (105
years), transgressive-regressive (T-R) cycles reflecting the
interplay between subsidence and sediment supply. We
focused on Cycle 6 of Anadon et al. (1985): two detailed
stratigraphic sections, one dose to the monastry (S. Benet
section) and the other in a more distai position (Calsina
section), were studied in terms of facies distribution and
sedimentary body geometries.
Three prominent stratigraphic surfaces, from bottom to
top, can be easily identified and laterally tracked across the
studied interval:
i) the lower boundary of the amalgamated, channel-fill
conglomerates, which is interpreted as the sequence
boundary, reflects significant erosion under low-accommodation
conditions. Fluvial incision was about 30m at S.
Benet, where the amalgamated conglomerate facies is
thickest. The incised valley body thins out distally, where
incision was reduced to 8 m.
ii) the top of the amalgamated conglomerates is a conformable
surface that displays the best correlation potential.
Despite its occurrence within alluvial deposits, this surface
can be easily recognized by the associated sharp facies
change from high net-to-gross, laterally extensive fluvial
bodies (lowstand systems tract) to the overlying, ribbonshaped
fluvial bodies encased within floodplain facies
(lower transgressive systems tract), and for this reason is
interpreted as the maximum regressive surface. The abrupt
decrease in the proportion and interconnectedness of the
fluvial bodies strongly indicates rapid creation of accommodation,
which is highly suggestive of "transgressive"
conditions.
iii) the surface of wave ravinement is an obvious stratigraphic
marker that can be easily detected in the field at
the transition from comparatively finer-grained, "transgressive"
alluvial and coastal plain deposits to the overlying
nearshore sandstones. The littoral sandstones are
invariably overlain by shallow-marine marly deposits
(upper transgressive systems tract), with upper transition
to a prograding deltaic succession (highstand systems
tract).
In terms of sequence-stratigraphic interpretation, the sharp
facies change interpreted here as the maximum regressive
surface represents an easily mappable surface across the
study area, which is much more readily identified than the
sequence boundary, thus supporting stratigraphic subdivision
of the Montserrat conglomerates into T-R sequences
(Burns et al., 1977)
Il territorio tra il Monte Monaco e il fiume Calore. Storia degli studi e delle ricerche. Il territorio nella cartografia storica
No full textIl contributo analizza la storia degli studi del territorio compreso nei comuni di Faicchio, Puglianello, Amorosi, S. Salvatore Telesino e Telese Terme, ai fini della redazione della Carta archeologica.The paper analyzes the archaeological studies on the municipalities of Faicchio, Puglianello, Amorosi, S. Salvatore Telesino and Telese Terme, for the Archaeological Map
An experimental investigation into the mechanical behaviour of a structured stiff clay
No full textIn recent years, fundamental research has been carried out into the properties of some natural stiff clays and the corresponding reconstituted materials, highlighting the role of microstructural features in the observed differences. In this paper the results of an experimental investigation into the mechanical behaviour of an Italian stiff clay of marine origin are presented. Medium-pressure and high-pressure stress-controlled triaxial cells were used in which natural samples underwent isotropic and anisotropic compression and swelling before drained or undrained shearing. Comparison of soil behaviour observed after different compression histories up to different values of maximum effective stress allowed the following aspects to be discussed: the effects of the initially structured state on the medium to large strain response and shear strength characteristics of the soil; the relevance of volumetric and deviatoric plastic strain to the structure degradation; the role and implications of the imposed non-isotropic stress histories; the permanent differences between reconstituted samples and fully destructured natural samples; and the uniqueness of the critical state condition
High-resolution sequence-stratigraphy of the post-LGM transgressive succession of the Arno valley fill (Tuscany, Italy)
No full textDespite recent report of millennial-scale cyclicity from
Lateglacial-Holocene deposits of severa! coastal plains
worldwide, no precise documentation ofthe key fac-
' tors controlling cyclic facies architecture has been
made available by previous work.
Integrated sedimentologic, micropalaentologic, palynologic
and geochemical analyses of a 56 m long core
(Sl) from the Pisa area (Tuscany, ltaly). allow reconstruction
of a high-resolution sequence-stratigraphic
framework for the transgressive systems tract (TST)
ofthe post-Last Glacial Maximum (LGM) succession
ofthe Arno valley fili.
At this location, the post-LGM succession is about
54 m thick and its lower part (early TST) includes a
35 m thick succession of alternating inner- and central-
estuarine deposits (sensu Dalrymple et al. 1992).
Three high-frequency depositional cycles, about 8-12
m thick and spanning intervals of ti me of about 1500
years each, are identified in core Sl. These cycles can
be physically traced throughout the valley body, grading
seaward to outer estuarine deposits (Amorosi et
al. 2008). Radiocarbon dates constrain the age ofthe
valley fili between 13 and 8 cal. kyr BP. Around 8 cal.
kyr BP, transgressive sedimentation spread onto the
interfluves and a coastal environment established ali
throughout the study area (late TST).
The three small-scale cycles are bounded by latera!
equivalents of marine flooding surfaces (parasequences)
and display a characteristic internai
architecture, with a thin transgressive central-estuarine
succession overlain by comparatively thicker,
regressive inner-estuarine deposits. Differentiation of
eight microfaunal (benthic foraminifer and ostracod)
associations, allows to refi ne the stratigraphic framework,
emphasizing subtle changes in palaeosalinity
across parasequence boundaries.
Diagnostic changes in vegetation patterns, driven
by opposite climate conditions, enable precise documentation
of parasequence development as a function
of climate change around the Pleistocene-Holocene
boundary. Pollen spectra invariably show expansions
of broad-leaved forests at parasequence boundaries,
suggesting that rapid shifts to warmer climate conditions
accompanied episodes of rapid sea-level rise.
In contrast, sti llstand phases saw the development of
cold-temperate communities (upper parts of parasequences),
suggesting transition to temporary colder
climate conditions.
Geochemical characterization of the three parasequences
allows detailed recon struction of palaoenvironmental
changes within the valley, as a function
of small-scale sea-level fluctuations. Specifically,
peaks in [Cr/Ba]/[Mg/Al] at the onset ofbrackish conditions
(lower parts of parasequences) are interpreted
to reflect a major sediment contribution from the Arno
River to the estuary during transgressive pulsations.
In contrast, sediment provenance from Serchio River
is recorded by the upper parts ofparasequences. This
suggests increasing sediment contribution from atributary
incised valley at times of sea-level stillstand,
accompanying coastal progradation
Small-strain stiffness of reconstituted clay compressed along constant triaxial effective stress ratio paths
No full textThe work described in the paper is an experimental investigation of the effects of anisotropic stress states and histories on the small-strain shear stiffness of reconstituted clays as measured with bender element tests. A brief review is made of previous work dealing with the dependence of small-strain shear modulus on stress state and history in isotropic conditions of confinement, and the rational link that exists between void ratio, e, effective stress, sigma', and overconsolidation ratio, OCR, is considered. Under isotropic stress conditions, only two out of the three variables e, sigma' and OCR are required to describe the dependence of the small- strain stiffness of a clay on current state and history. The same approach proved useful in the analysis of the data from tests with anisotropic stress conditions. The values of the small- strain shear modulus of reconstituted samples compressed along stress paths with constant triaxial effective stress ratios were higher than those measured on isotropically compressed samples. The observed differences increased with increasing stress ratio and could be explained only in part in terms of the smaller void ratios of the anisotropically compressed samples at the same mean effective stress. Simple relationships to evaluate the stiffness indexes of clays that have undergone anisotropic stress histories are proposed
Small-strain stiffness of reconstituted clay compressed along constant triaxial stress ratio paths
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