Soil-structure interaction during tunnelling in urban area: observations and 3D numerical modelling

Fargnoli, Valentina (2015) Soil-structure interaction during tunnelling in urban area: observations and 3D numerical modelling, [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Ingegneria civile, ambientale e dei materiali, 27 Ciclo. DOI 10.6092/unibo/amsdottorato/6926.
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Abstract

This work illustrates a soil-tunnel-structure interaction study performed by an integrated,geotechnical and structural,approach based on 3D finite element analyses and validated against experimental observations.The study aims at analysing the response of reinforced concrete framed buildings on discrete foundations in interaction with metro lines.It refers to the case of the twin tunnels of the Milan (Italy) metro line 5,recently built in coarse grained materials using EPB machines,for which subsidence measurements collected along ground and building sections during tunnelling were available.Settlements measured under freefield conditions are firstly back interpreted using Gaussian empirical predictions. Then,the in situ measurements’ analysis is extended to include the evolving response of a 9 storey reinforced concrete building while being undercrossed by the metro line.In the finite element study,the soil mechanical behaviour is described using an advanced constitutive model. This latter,when combined with a proper simulation of the excavation process, proves to realistically reproduce the subsidence profiles under free field conditions and to capture the interaction phenomena occurring between the twin tunnels during the excavation. Furthermore, when the numerical model is extended to include the building, schematised in a detailed manner, the results are in good agreement with the monitoring data for different stages of the twin tunnelling. Thus, they indirectly confirm the satisfactory performance of the adopted numerical approach which also allows a direct evaluation of the structural response as an outcome of the analysis. Further analyses are also carried out modelling the building with different levels of detail. The results highlight that, in this case, the simplified approach based on the equivalent plate schematisation is inadequate to capture the real tunnelling induced displacement field. The overall behaviour of the system proves to be mainly influenced by the buried portion of the building which plays an essential role in the interaction mechanism, due to its high stiffness.

Abstract
Tipologia del documento
Tesi di dottorato
Autore
Fargnoli, Valentina
Supervisore
Co-supervisore
Dottorato di ricerca
Scuola di dottorato
Ingegneria civile ed architettura
Ciclo
27
Coordinatore
Settore disciplinare
Settore concorsuale
Parole chiave
twin tunnels, EPB tunnelling, settlements, coarse-grained soils, Milan metro line 5, monitoring data, soil structure interaction, 3D numerical modelling, soil constitutive modelling, structural modelling, reinforced concrete framed buildings, discrete foundations, equivalent plate
URN:NBN
DOI
10.6092/unibo/amsdottorato/6926
Data di discussione
21 Maggio 2015
URI

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