No abstract

No abstract

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

Computational modelling of the effect of underground excavations on adjacent structures has shown great potential to aid the assessment of tunnelling-induced damage to structures. However, the complexity of the mechanisms involved and the uncertainties connected to the use of sophisticated constitutive laws still limit the application of numerical modelling in civil engineering practice. This paper evaluates the effectiveness of soil models with different levels of complexity when predicting tunnelling-induced displacements of the soil surface, and consequently the assessment of building deformations. The performance of a non-linear elastic, a linear elastic–perfectly plastic and a critical-state-based kinematic hardening soil model were compared with the results of centrifuge testing of a tunnel excavation in sand. Results demonstrated that both the non-linear elastic and the kinematic hardening models are suitable to reproduce the effect of soil–structure interaction on the soil surface displacements and the building deformations, while also demonstrating the limitations of these methods in predicting local soil strains around the tunnel itself.

This paper investigates the influence of the foundation configuration (raft or separate footings) on tunnel-soil-framed building interaction 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 is 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.