1,721,032 research outputs found
Geotechnical design and construction issues for Lines 1 and 6 of the Naples Underground
No full textSince 1839, when the historical railway Naples - Portici was inaugurated, Naples has been characterized by a significant system of urban and suburban railways. The idea of a fully integrated urban rail network dates back to the 1950s, but construction only began in the 1990s. At present, the system includes 54 km of tracks and 69 stations in operation; ten lines with 93 km of track and a further 30 km of new light rail linking 114 stations with 21 interchanges are planned with the completion of the City Transport Plan.
The present paper reports on some geotechnical aspects of the design and construction of Lines 1 and 6, which are presently underway, discussing how the experience gathered during construction of Line 1 influenced some of the design choices for Line 6
Scavo di galleria in area urbana: modellazione fisica e numerica
No full textNella presente nota sono illustrati i risultati di una ricerca riguardante la modellazione fisica e numerica dello scavo di una galleria in condizioni di campo libero e in presenza di un elemento strutturale. Lo studio è finalizzato alla verifica dell’efficacia di strumenti di analisi numerica di tipo convenzionale per la simulazione dei risultati di prove su modello fisico in scala ridotta, eseguite nella centrifuga geotecnica del London Geotechnical Centrifuge Centre (LGCC) della City University di Londra
Evaluating the effects of tunnelling on hystorical building: The example of a new subway in Rome
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Grading evolution of an artificial granular material from medium to high stress under one-dimensional compression
Full text linkThis contribution presents the results of an experimental investigation of the mechanical behaviour of granular materials with crushable grains under one-dimensional compression at medium to high stress. The material used for the experimental work is a Light Expanded Clay Aggregate (LECA) whose grains break at relatively low stress. Reconstituted samples were prepared with different initial grain size distributions and their evolution observed under one-dimensional compression. The grain size distributions before and after testing were used to calibrate a bimodal model obtained from the superposition of two Weibull functions. The observed evolution of the micro and macro diameters on loading are linked to the characteristics of the one-dimensional compressibility curve obtained under displacement controlled conditions, such as its shape and two characteristic stress values, namely the pre-consolidation stress and the stress corresponding to the point of inflection
The crossing of the historical centre of Rome by the new underground Line C: a study of soil structure-interaction for historical buildings
No full textThis work deals with the soil structure-interaction problems posed by the construction
of the third line of Roma underground (Line C), which, in its central stretch, crosses
the historical centre of the city with significant interferences with the archaeological and
monumental heritage. The paper describes the methodological approach developed to evaluate
the effects of tunnelling on the existing monuments and historical buildings, starting from a
careful geotechnical and structural characterisation and including the development of reliable
geotechnical and structural models. Experts in several disciplines were committed to this multidisciplinary
work, ranging from geologists to geotechnical and structural engineers, archaeologists,
and professionals working in the field of conservation and restoration of works of art and
monuments. The study of the interaction between the construction activities and the built environment
was carried out following procedures of increasing level of complexity, from green
field analyses, in which the stiffness of the existing buildings was neglected, to full soilstructure
interaction analyses, performed in both two- and three-dimensional conditions, accounting
for the stiffness of existing buildings and considering possible long-term effects. The
paper illustrates the main aspects of this procedure, using the example case studies of the Basilica
di Massenzio and of the building of the Amministrazione Doria Pamphili
Seismic behaviour of retaining structures: from fundamentals to performance-based design
No full textGuidelines 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 ground. © 2012 Taylor & Francis Group
A fractal analysis method to characterise rock joint morphology
Full text linkRock joints morphological characteristics strongly influence the shear strength dilatancy response of the discontinuity. Morphological features of rock joints are commonly identified with a roughness descriptor along standard 100 mm-length profile detected by instrumentation such as profilometers. This work extends a method proposed for fractal analysis of particle contours to describe rock joint profiles in terms of quantitative descriptors of their roughness. It is well-established that natural surfaces have a fractal nature, self similar over a wide range of scales. This implies that the measured length of their outline is a function of the measurement scale: the smaller the measurement scale, the longer the profile length. Based on the interpretation of the fractal analysis of rock joint profiles, relating the length of the profile to the measurement scale, descriptors identifying the roughness and its characteristic scale are proposed. The method is first applied to some artificial profiles, and later to real rock joint profiles
Interaction domains of pile groups in cohesive soils under generalised loads
No full textThis work focuses on the undrained bearing capacity of pile groups subjected to combined vertical, moment, and lateral loads. Advanced 3D FE analyses were used to identify the possible plastic mechanisms occurring within the soil-foundation system, as well as the most relevant factors affecting its limit behaviour. The numerical results show a strong coupling between the lateral capacity of the group and the applied vertical/moment loads, resulting from a different degree of mobilisation of the axial and bending capacity of the piles. Based on the numerical findings, a new theoretical lower bound solution was developed to compute the 3D failure domain of pile groups in clay, overcoming limitations and inconsistencies of theoretical solutions recently proposed in the technical literature. The method accounts for the combined effect of group geometry, structural and geotechnical capacity of the single piles, and loading direction on the actual plastic mechanism occurring within the group and the corresponding failure envelope
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