1,721,098 research outputs found
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
Monitoraggio 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
Discussion: Effect of soil models on the prediction of tunnelling-induced deformations of structures
No full textGreen Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Geo-engineerin
Experiences gathered from the construction of Napoli underground
Full text linkThe 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
Finite element analysis of the excavation of the new Stazione Garibaldi of Napoli Underground
No full textThis paper describes the excavation for the new Garibaldi Station of Napoli Underground, completed in October 2004. The 44 x 20 m2 rectangular excavation, with a maximum depth of 45 m bgl., was protected by 1 m thick concrete diaphragm walls excavated using a hydromill, in 2.5 m wide panels. The excavation was carried out top down, support being provided by the floors of the station and by several levels of anchors. The paper describes a finite element analysis of the construction of the structure and a comparison of the numerical predictions with the observed behaviour. Before modelling the main sequence of excavation and propping and the changes of pore water pressures due to the excavation works, the sequence of panel excavation under bentonite slurry and concreting was examined. A significant effect of modelling wall installation versus wished in place wall analyses was found in terms of displacements of the wall and ground surface at the back of the wall, prop forces and bending moments within the wall. The available measurements were used both to assess the numerical predictions, in terms of diaphragm displacements, and to guide in the way in which some support elements, e.g. anchors, should be treated in the analyses
Una soluzione analitica per la componente rotazionale dell'eccitazione sismica dovuta all'interazione cinematica pali-terreno
No full textNella nota si affronta il problema della componente rotazionale dell’eccitazione sismica alla base di una struttura
dovuta all’interazione cinematica fra terreno e pali di fondazione. Viene illustrato un semplice modello analitico,
in cui il moto rotazionale del gruppo di pali è espresso in funzione della sola risposta cinematica del palo isolato
libero di ruotare. Si presentano alcune semplici espressioni per le due componenti traslazionale e rotazionale del
moto sismico risultante dall’interazione cinematica, nel caso di pali identici distribuiti in modo regolare o casuale
e connessi da un elemento di collegamento infinitamente rigido. La soluzione proposta, applicabile anche al caso
di sottosuolo stratificato, mostra che il moto rotazionale alla base di una struttura fondata su pali dipende
prevalentemente dalla distribuzione dei pali e dalle componenti di rigidezza del palo isolato. Si presenta infine
un’applicazione della soluzione analitica al caso di un edificio alto fondato su pali, mostrando come la componente
rotazionale possa, in alcuni casi limite, comportare un incremento della domanda sismica rispetto al caso ideale
nel quale si applica alla base dell’edificio direttamente il moto di free-field
Managing knowledge for future-proof tunnels in The Netherlands
No full textThe COB is The Netherlands Knowledge Centre for Underground Construction and Underground Space. Over sixty organisations, from government, industry and knowledge institutes, work together to learn and develop smart solutions regarding tunnels. This network has developed a long-term vision on tunnels in The Netherlands. As a result, nineteen tunnels and all stakeholders collaborate on eight research topics of our tunnel programme. We found common ground and the key issues are already being addressed in both practice and science. Topics include risks, construction failure, modular renovation, digital tunnel twin, virtual testing, virtual education and system safety. The way clients, science and industry work together within the COB network has been a major precondition to achieve these great results in such a short period of time.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Geo-engineerin
Settlements of immersed tunnel on soft ground: A case study
No full textThis paper focuses on the settlement analysis of immersed tunnel on soft ground. Even under careful design, immersed tunnel may have problems of excessive settlement and the resulting concrete cracking or structure leakage during operation period. Yongjiang Tunnel, the first immersed tunnel on soft ground in mainland China, is taken as a case study. The monitored settlement data after a 16-year service is first displayed and analyzed, then a 2D numerical model is built to simulate the ground settlement deformation from tunnel construction to long-term tunnel operation. The effects of back-silting on the stiffness of the foundation layer and further on the settlement is quantitatively analyzed, and the advices on settlement control for immersed tunnel on soft ground are provided.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Geo-engineerin
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