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Criteria for numerical modelling of very stiff cantilever retaining structures

Di Sotto Antonello Miliziano Salvatore
Articolo Immagine
ISSN:
0557-1405
Rivista:
Rivista Italiana di Geotecnica
Anno:
2014
Numero:
3
Fascicolo:
Rivista Italiana di Geotecnica N. 3/2014

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L’articolo ha per oggetto l’illustrazione del comportamento di tre tipi di paratie a sbalzo molto rigide in terreni sabbiosi ottenuto mediante modellazione numerica. Queste tipologie di strutture sono frequentemente impiegate per il sostegno degli scavi al fine di minimizzare gli spostamenti del terreno in ambiente urbano, dove l’impiego di tiranti spesso non è perseguibile. Il comportamento degli elementi strutturali, simulati sia come elementi beam sia come continuo, è ipotizzato elastico. Il comportamento meccanico del terreno è assunto elasto-plastico perfetto e privo di dilatanza. Con riferimento alle condizioni di esercizio vengono confrontati gli spostamenti e le sollecitazioni sugli elementi strutturali ottenuti per le differenti soluzioni studiate e per i differenti approcci impiegati (beam e continuo). L’accuratezza dei risultati è assicurata mediante analisi di convergenza. Lo studio chiarisce il ruolo cruciale svolto dalle tensioni tangenziali mobilitate al contorno degli elementi strutturali conseguenti all’esecuzione degli scavi e fornisce indicazioni per la messa a punto di modelli numerici capaci di simulare accuratamente il comportamento di queste particolari strutture ai fini applicativi.

This paper focuses on the main results obtained from studying, via numerical simulations, three different solutions of very stiff cantilever retaining structures in sandy soil. These structures are usually employed to support deep excavations to minimize soil displacement in urban areas where the use of anchors is often impossible. Structural elements are assumed to be elastic and are simulated by both beam and continuum elements. A simple elastic perfectly plastic constitutive model with Mohr-Coulomb strength criterion and zero dilatancy is used to describe soil behaviour. The stress and displacement fields in structural elements under normal loading conditions for the different solutions and approaches adopted (beam or continuum) are reported and compared. Numerical analyses are also carried out to investigate failure mechanisms. The accuracy of the results is checked by convergence analyses. The study highlights the crucial role played by the shear stresses mobilized at the boundary of structural elements due to excavation. Guidance is offered to develop models to numerically obtain accurate behaviour of these kinds of structures in practice.

This paper focuses on the main results obtained from studying, via numerical simulations, three different solutions of very stiff cantilever retaining structures in sandy soil. These structures are usually employed to support deep excavations to minimize soil displacement in urban areas where the use of anchors is often impossible. Structural elements are assumed to be elastic and are simulated by both beam and continuum elements. A simple elastic perfectly plastic constitutive model with Mohr-Coulomb strength criterion and zero dilatancy is used to describe soil behaviour. The stress and displacement fields in structural elements under normal loading conditions for the different solutions and approaches adopted (beam or continuum) are reported and compared. Numerical analyses are also carried out to investigate failure mechanisms. The accuracy of the results is checked by convergence analyses. The study highlights the crucial role played by the shear stresses mobilized at the boundary of structural elements due to excavation. Guidance is offered to develop models to numerically obtain accurate behaviour of these kinds of structures in practice.