Numerical analysis of the tunnelling with emphases in the ground-support interaction in shotcrete at early ages / Análise numérica de escavações subterrâneas com ênfase na interação entre o maçiço e o suporte em concreto projetado a baixas idades

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

This thesis presents a numerical analysis of the ground/support interaction, considering the transient behavior of the shotcrete while the gradual loading of the support occurs, due to progressive advance of the excavation face. The numerical analyses were carried out according to the finite elements method in tunnelling with circular section, under various configurations of covering, free length and behavior of the ground, under saturated condition. In simulations, it was considered the continuous support in shotcrete, with its mechanical properties increasing in time and the support in precast concrete, with final mechanical properties in the hard state. The loading transference evaluation of the ground for the support was made with three-dimensional numerical analyses, with the soil modelled by the Mohr-Coulomb and Hardening Soil models, considering different modules of deformability. For considering conditions of unloading and reloading, the model Hardening Soil pointed a lesser loading level with respect to the support, over all for the bending forces. The structural verification of the support was made considering the flexo-compression method, from the solicitant internal forces in the support sections (bending moment and normal force), according to dimensionless graphs of interaction between these two forces. The method proposed for MELLO (2003) was used, had as one of the only methods that provides an analytical solution of the non linear equations that govern the conditions of balance and resistance of the transversal section, using the rectangular diagram equivalent of the concrete. The comparison of the interactions results between bending moment and normal force for the tunnel support in the simulations considering the concrete (shotcrete) hardening and the concrete with constant rigidity (precast concrete) show a scene of greater security for the first case. Although in the early hours, the concrete does not have satisfactory resistance to loadings, these loadings are smaller than those transferred by the ground to the support when the 28 days rigidity concrete is admitted.

ASSUNTO(S)

geotecnica obras subterrâneas concreto projetado métodos numéricos interação solo-estrutura

ACESSO AO ARTIGO

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