Abstract
The interaction mechanisms between surface structures and tunnelling-induced ground movements were investigated through centrifuge testing. Although numerous studies have considered this soil–structure interaction problem, previous experiments have neglected important building characteristics and field data inherently contain numerous uncertainties related to the soil, the structure and the tunnelling procedure. Consequently, the interpretation of results and validation of computational models can be problematic. In this study, tunnelling beneath three-dimensional printed structural models with varying building characteristics (i.e. position, length and facade openings) was simulated in a centrifuge. The experimental results demonstrate that tunnelling induces soil displacements at the surface and subsurface that are notably altered due to nearby structures. Specifically, different amounts of vertical and horizontal ground movements, soil dilation and widening of settlement troughs were observed. Building distortions and horizontal building strains were also affected by the relative position of the building to the tunnel, the building length and the area of facade openings. The experimental results provide important data for the evaluation of current design methods and verification of computational models.
Highlights
Predicting building response to tunnelling-induced settlement is essential for urban tunnelling projects, but remains a challenge due to the complex soil–structure interaction
The greenfield settlement profiles transverse to the tunnel are described by a Gaussian curve (Peck, 1969; Schmidt, 1969). These settlement profiles are predicted by making assumptions on the tunnelling-induced ground loss and the width of the settlement trough, which both depend on the tunnelling method and the ground conditions
The potential soil– structure interaction during the tunnelling procedure is considered using modification factors, which quantify the alteration of greenfield displacements as a function of the given relative building stiffness
Summary
Predicting building response to tunnelling-induced settlement is essential for urban tunnelling projects, but remains a challenge due to the complex soil–structure interaction. Parametric studies have enabled the translation of such modelling results into empirical design methods (Potts & Addenbrooke, 1997; Franzius et al, 2006; Goh & Mair, 2012; Giardina et al, 2015a) These so-called relative stiffness approaches, which relate the building stiffness to the soil stiffness, compare the actual settlements with the settlements in greenfield conditions, where no buildings are present. Mεht 1⁄4 εht;Str εht;GF ð2aÞ ð2bÞ where εhc and εht are the compressive and tensile horizontal strains of the structure (Str) or the greenfield equivalent (GF) These relative building stiffness methods highlight the soil–structure interaction effects, surface structures are simplified as elastic beams and building characteristics (e.g. facade openings or non-linear material behaviour) are not considered. The results of a greenfield test performed by Farrell (2010), which replicated the identical tunnelling prototype, are presented in this paper
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