207 research outputs found
Soil-structure interaction for the seismic design of the Messina Strait Bridge
No full textThis paper illustrates an approach to the study of the seismic soil–structure interaction that was
developed at the verification stage of the design of the Messina Strait Bridge in order to validate its
seismic behaviour. It consisted of a series of two-dimensional, plane strain numerical analyses on models
that included, in addition to the embedded foundation elements, a simplified structural description of
the bridge towers: simplified structural models were specifically designed to reproduce the first
vibrations modes of the towers, that were deemed to have the most significant influence on the
system's dynamic response. Non-linear dynamic analyses were carried out in the time domain, studying
the effects of two different natural records, each characterised by three orthogonal components of the
soil motion. In the first part of the paper, essential information is provided about the foundations layout,
the main properties of the foundation soil resulting from the in situ and laboratory investigation, and the
assessment of the liquefaction potential. Then, the numerical models are discussed in some detail, with
an emphasis on the modelling of the soil and of the structural elements. For sake of conciseness, details
are provided only for one of the two shores. The results obtained with the present approach shed some
light on the complex coupling between the soil's and the structure's behaviour, evidencing the significant
role that the embedded, massive foundations of the bridge play in the dynamic response of the system.
The computed time-histories of the displacements of the foundation elements are used to assess the
seismic performance of the bridge
Experiences gathered from the construction of Napoli underground
No full textThe design of a deep excavation must address a number of issues such as, for instance, the choice of an adequate support system, the definition of the sequence of construction phases, the computation of the stresses in the structural members, and the evaluation of the magnitude and distribution of ground displacements connected to the construction phases and to possible changes of groundwater pressures connected with the excavation. Under these premises, in the paper it is presented a summary of the main results obtained by an intense monitoring program carried out in the occasion of the construction of deep excavations in the densely urban environment of Napoli (Italia) for the completion of the existing Underground Line 1
Guidelines for comparing field or physical model observations with numerical simulations
No full textThis paper presents short report on the activities of TC204 Working Group on "Guidelines to compare field or physical model observations with numerical simulations". The main objective of the WG is that of proposing recommendations concerning the comparison between calculated and observed behaviour, specifically adapted for the type of works covered by TC204, i.e. tunnels and open excavations in soft groun
Numerical modelling of installation effects for diaphragm walls in sand
No full textThe scopes of this work are to study the mechanisms of load transfer and the deformations of the ground during slurry trenching and concreting in dry sand and to evaluate their effects on service structural loads, wall deflections and ground displacements behind the wall caused by subsequent excavation. A series of three-dimensional finite element analyses was carried out modelling the installation of diaphragm walls consisting of panels of different length. The soil was modelled as either linearly elastic-perfectly plastic or incrementally non-linear (hypoplastic) with elastic strain range. Plane strain analyses of diaphragm walls of identical cross section were also carried out in which wall installation was either modelled or the wall was wished in place (WIP). The analyses predict ground movements consistent with the experimental observations both in magnitude and trend. The results also show that the maximum horizontal wall deflections and structural loads reduce with increasing panel aspect ratio towards a minimum which is about twice the value computed for WIP analyses. Panel aspect ratios should be larger than about three to take advantage of the three-dimensional effects. The pattern and magnitude of surface vertical displacements obtained from linearly elastic-perfectly plastic analyses, no matter whether three- or two-dimensional, are unrealistic
Predicting the seismic behaviour of the foundations of the Messina Strait Bridge
No full textThis paper presents some of the geotechnical studies carried out for the seismic design of the one-span suspension bridge across the Messina Strait, that is to connect Sicily with mainland Italy. These studies included advanced geotechnical characterisation, through in situ and laboratory tests, estimate of site stability involving both liquefaction analysis and submerged slope stability, evaluation of soil-foundation stiffness for spectral analysis of the superstructure, 3D FE static calculations, evaluation of anchor block performance under seismic conditions, and full dynamic analyses of the soil-structure interaction. The paper summarises the main results obtained from the geotechnical characterisation of the foundation soils, reports the approach adopted for evaluating the seismic performance of the anchor blocks through a modified Newmark-type calculation, and presents the study of the soil-structure interaction carried out through a series of two-dimensional, plane strain numerical analyses. In these analyses, in addition to the embedded foundation elements, the models included a simplified structural description of the bridge towers specifically designed to reproduce their first vibrations modes, that were deemed to have the most significant influence on the system's dynamic response. The illustration is limited to the foundation systems of the bridge located on the Sicily shore
Introduzione all'ingegneria geotecnica - Meccanica dei terreni e delle rocce (titolo originale: the mechanics of soils and foundations)
No full textMonitoraggio di Scavi: L'esperienza della Linea 1 della Metropolitana di Napoli. RELAZIONE DI PANEL
No full textGeotechnical aspects of undeground railway construction in the urban environment: The examples of Rome and Napoli. GENERAL REPORT
No full textThis paper presents some of the geotechnical aspects of underground railway construction in the urban environment, drawing from recent experience gathered during the design of the new Line C of Rome Underground and the construction of Line 1 of Naples Underground. For Rome Underground, the paper summarizes the main results of a study of the interaction between tunnel construction and a monumental structure at the surface. The assessment of the potential damage induced by tunnelling was approached following stages of increasing complexity, from simple and well-established semi-empirical methods to 2D and 3D numerical soil-structure interaction analyses. A significant joint effort from archaeologists and geotechnical and structural engineers was required to define reliable models of the monument and of the subsoil ground conditions. For Naples Underground, this paper describes the construction techniques that were implemented to build the open excavations required to accommodate the stations, including artificial ground freezing, and illustrates some of the analyses that were carried out to interpret the observations of the ground behaviour and of the behaviour of the structures during construction
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