Development and testing of a simplified building model for the study of soil-structure interaction due to tunnelling in soft ground

Lo scavo di gallerie in ambiente urbano induce inevitabilmente degli spostamenti a livello delle fondazioni degli edifici. La previsione degli spostamenti causati dall'interazione galleria-terreno-struttura viene di solito effettuata mediante analisi numeriche. Lo studio degli effetti di tali spostamenti sulla struttura in elevazione è particolarmente importante quando gli edifici interessati sono caratterizzati da grande valore storico-artistico, come è spesso il caso nei centri stroici delle città. In presenza di edifici particolarmente sensibili si rende necessario procedere alla modellazione di dettaglio della struttura per cogliere gli effetti in elevazione, anche localizzati. Inoltre, la geometria del problema esaminato può rendere necessario lo svolgimento di analisi tridimensionali, con evidente aggravio in termini di potenza e tempi di calcolo richiesti. Una semplificazione delle analisi è auspicabile, soprattutto in presenza di numerosi edifici. In questa tesi si propone di effettuare lo studio dell'interazione utilizzando nelle analisi numeriche una rappresentazione semplificata dell'edificio esaminato detta ``solido equivalente''. In particolare il lavoro è mirato alla definizione del solido equivalente e all'identificazione dei relativi parametri meccanici. L'uso del solido equivalente nelle analisi di interazione fornisce cedimenti in buon accordo con quelli ottenuti utilizzando un modello completo dell'edificio. I cedimenti ricavati alla base del solido equivalente, dunque, potranno essere successivamente applicati in maniera disaccoppiata alla base di un modello adeguatamente dettagliato dell'edificio, demandando in questo modo ad una fase successiva dello studio l'esame degli effetti sulla struttura in elevazione

Development and testing of a simplified building model for the study of soil-structure interaction due to tunnelling in soft ground

Lo scavo di gallerie in ambiente urbano induce inevitabilmente degli spostamenti a livello delle fondazioni degli edifici. La previsione degli spostamenti causati dall'interazione galleria-terreno-struttura viene di solito effettuata mediante analisi numeriche. Lo studio degli effetti di tali spostamenti sulla struttura in elevazione è particolarmente importante quando gli edifici interessati sono caratterizzati da grande valore storico-artistico, come è spesso il caso nei centri stroici delle città. In presenza di edifici particolarmente sensibili si rende necessario procedere alla modellazione di dettaglio della struttura per cogliere gli effetti in elevazione, anche localizzati. Inoltre, la geometria del problema esaminato può rendere necessario lo svolgimento di analisi tridimensionali, con evidente aggravio in termini di potenza e tempi di calcolo richiesti. Una semplificazione delle analisi è auspicabile, soprattutto in presenza di numerosi edifici. In questa tesi si propone di effettuare lo studio dell'interazione utilizzando nelle analisi numeriche una rappresentazione semplificata dell'edificio esaminato detta ``solido equivalente''. In particolare il lavoro è mirato alla definizione del solido equivalente e all'identificazione dei relativi parametri meccanici. L'uso del solido equivalente nelle analisi di interazione fornisce cedimenti in buon accordo con quelli ottenuti utilizzando un modello completo dell'edificio. I cedimenti ricavati alla base del solido equivalente, dunque, potranno essere successivamente applicati in maniera disaccoppiata alla base di un modello adeguatamente dettagliato dell'edificio, demandando in questo modo ad una fase successiva dello studio l'esame degli effetti sulla struttura in elevazione

Protecting surface and buried structures from tunnelling using pile walls: a prediction model

When tunnelling poses excessive risks for buildings and buried foundations, a pile row barrier may shield the existing structure from ground movements. This paper presents a three-dimensional linear elastic prediction method to evaluate the protective action of pile walls against surface and subsurface ground movements due to new tunnels, both directly behind the wall as well as within the entire ground. Analyses are carried out to evaluate the vertical and horizontal movements of the ground and the pile wall as the result of soil-pile row interaction. New factors that quantify the wall efficiency in reducing settlements and deflections behind the wall are proposed; the results indicate that the effectiveness of the pile wall at reducing horizontal displacements is limited. Subsequently, predictions are compared against field and numerical data to demonstrate that the elastic solution is applicable, particularly for small ground losses. Finally, the barrier efficiency in reducing settlements is discussed comparing pile walls and diaphragm walls

Role of Footing Embedment on Tunnel–Foundation Interaction

This technical note investigates the effect of footing embedment depth on tunnel-structure interaction using geotechnical centrifuge testing. A two-story framed building on separate footings, either resting directly on the surface or embedded in the soil, and subjected to tunneling induced displacements is modeled. Measurements of the displacements of the footings and underlying soil, ground deformations, and structural distortions are presented. Results show that footing embedment increases foundation differential settlements and horizontal displacements, thereby causing a greater level of distortion within the frame. Furthermore, the embedded footings result in a larger magnitude of ground displacements and shear strains of the soil. Finally, modification factors and relative stiffness parameters are presented, indicating a greater effect of the embedment on horizontal deformations than the angular distortion of the bays

Soil-structure interaction due to tunnelling in soft ground, an equivalent solid approach

This paper presents a partly uncoupled procedure for the evaluation of tunnelling induced damage on historic buildings, focusing on Roman Renaissance masonry structures in particular. Soil-structure interaction is studied through finite element analyses using a simplified model of the examined building, called ‘equivalent solid’. The equivalent solid model consists of the part of the building embedded in the soil and has a transverselyisotropic linear-elastic behaviour, with adequately calibrated moduli. Results of soil-structure interaction analyses show that, as far as the volume loss is in the typical range expected for tunnel excavation with an earth pressure balance shield, the equivalent solid yields approximately the same settlement distribution as a detailed structural model. Then, damage assessment is carried out applying the predicted settlements at the base of a detailed model of the building that takes into account material non-linearity

Uncoupled evaluation of the structural damage induced by tunnelling

This paper illustrates an approximate procedure for the evaluation of the damage induced on existing buildings by the excavation of a tunnel. The method hinges on the development of a simplified structural model of the building, that can be readily incorporated into the finite-element mesh used to simulate the excavation of a tunnel. A first part of the article is devoted to the description of the equivalent structure and to the illustration of an identification procedure for the evaluation of its mechanical properties, based on appropriate scaling of the areal and inertial characteristics of the parent building. Then, the practical use of the method is illustrated by carrying out a series of three-dimensional numerical analyses of the excavation of an EPB tunnel, that include either the simplified or the fully detailed structural model of a masonry building. Using the results obtained with the complete building as a reference, it is shown that the simplified formulation is quite effective in capturing the main features of the soil-structure interaction for the problem at hand. Cases in which the method is less successful are discussed as well, indicating a suitable adjustment of the identification procedure for the simplified structural model

Modelling of Reinforced Concrete Framed Structures Interacting with a Shallow Tunnel

Abstract This paper deals with the numerical analysis of tunnelling-induced settlements on concrete framed structures founded on strip footings. In particular, a single frame with a variable number of storeys is taken into account in the present study, with an orientation perpendicular to the tunnel axis and a null eccentricity. The Finite Element simulations, carried out in three- dimensions with the code Abaqus, highlight the influence of the building stiffness and weight on the displacement field and provide an insight into the loading transfer mechanism occurring in the structural elements during tunnel excavation

Tunnel–framed building interaction: comparison between raft and separate footing foundations

In this paper, the influence of the foundation configuration (raft or separate footings) on tunnel–soil–framed building interaction is investigated using geotechnical centrifuge testing. Tunnelling-induced soil movements and deformation fields, framed building displacements and structure shear distortions (with associated modification factors) are illustrated. Framed building stiffness and footing bearing capacity are also evaluated experimentally. Results show that the foundation configuration plays an important role in determining the ground response to tunnelling, affecting soil displacement fields, as well as the distribution of soil shear and volumetric strains. In particular, foundation settlements and differential horizontal displacements are larger for separate footings compared to raft foundations. The effects of building width, weight and eccentricity (with respect to the tunnel) on foundation settlements and structural distortions are quantified for separate footings and contrasted against results for raft foundations. The modification factor of the maximum building shear distortion is linked to the relative soil–building shear stiffness; interestingly, for buildings with similar values of relative stiffness, the level of shear distortion within framed buildings is lower for separate footings than rafts

Discussion: Effect of soil models on the prediction of tunnelling-induced deformations of structures

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