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Summary: Structural deformation monitoring is crucial for the identification of early signs of tunnelling‐induced damage to adjacent structures and for the improvement of current damage assessment procedures. Satellite multi‐temporal interferometric synthetic aperture radar (MT‐InSAR) techniques enable measurement of building displacements over time with millimetre‐scale accuracy. Compared to traditional ground‐based monitoring, MT‐InSAR can yield denser and cheaper building observations, representing a cost‐effective monitoring tool. However, without integrating MT‐InSAR techniques and structural assessment, the potential of InSAR monitoring cannot be fully exploited. This integration is particularly demanding for large construction projects, where big datasets need to be processed. In this paper, we present a new automated methodology that integrates MT‐InSAR‐based building deformations and damage assessment procedures to evaluate settlement‐induced damage to buildings adjacent to tunnel excavations. The developed methodology was applied to the buildings along an 8‐km segment of the Crossrail tunnel route in London, using COSMO‐SkyMed MT‐InSAR data from 2011 to 2015. The methodology enabled the identification of damage levels for 858 buildings along the Crossrail twin tunnels, providing an unprecedented number of high quality field observations for building response to settlements. The proposed methodology can be used to improve current damage assessment procedures, for the benefit of future underground excavation projects in urban areas. [ABSTRACT FROM AUTHOR]

Tunnelling in urban areas requires a careful estimation of the consequence of soil settlements on existing buildings. In this paper the interaction between the excavation of a tunnel in sand and surface structures is investigated. A two dimensional finite element model is presented and validated through comparison with centrifuge test results, both with and without structures. The model is then used to perform a sensitivity study on the effect of building weight on soil movements and structural deformations. The results of the validation indicate that assuming a no-tension interface between the soil and the structure is essential to capture the soil–structure interaction that was experimentally observed. The parametric analyses show that the relation between the building stiffness and the tunnelling-induced deformations depends on the building weight. [ABSTRACT FROM AUTHOR]

This discussion considers the procedure proposed by Haji, Marshall and Tizani for the assessment of the structural stiffness of frame structures subjected to tunnelling. The discussion focuses on the potential contribution of both shear and bending flexibilities to the response of frame structures to tunnelling, as well as the role of the foundation scheme on the boundary conditions at the base of the structure. The validity of applying the proposed set of equations within currently available methods of prediction of tunnelling-induced deformations, based on modification factors, is also discussed. [ABSTRACT FROM AUTHOR]

Summary: The increasing demand for underground infrastructure should be supported by innovation in monitoring and damage assessment solutions to minimise damage to surface structures caused by ground settlements. This paper evaluates the use of multitemporal synthetic aperture radar interferometry (MT‐InSAR) to calculate tunnelling‐induced deformations of buildings. The paper introduces a step‐by‐step procedure to use InSAR displacements as an input to the structural damage assessment. After a comparison between traditional and InSAR monitoring data for the London area during the Crossrail excavation, the high resolution, high density InSAR‐based displacements were used to evaluate the building deformations for a number of case studies. Results demonstrate the quality of information provided by InSAR data on soil‐structure interaction mechanisms. Such information, essential to evaluate current damage assessment procedures, is typically only collected for relatively few buildings due to the cost of traditional monitoring. A comparison between damage indicators derived from greenfield assumptions and building displacements quantifies the practical benefit of the proposed step‐by‐step procedure. This work aims at filling the gap between the most recent advances in remote sensing and the civil engineering practice, defining the first step of an automated damage assessment procedure which can impact large scale underground projects in urban areas. [ABSTRACT FROM AUTHOR]

• Modelling tunnel-structure-interaction with Timoshenko beams founded on elastic continuum. • Effects of shear flexibility quantified in terms of displacements and deformations. • The offset between beam axis the ground level can impact the interaction problem. • The 'direct strain based approach' was proposed to infer maximum building strains. • Design charts with bending and shear structural stiffness as well as foundation shape ratio. Timoshenko beam theory and the limiting tensile strain method are implemented into the computer program ASRE for the coupled analysis of building response to tunnelling using an elastic two-stage analysis method. A framework to characterise an equivalent Timoshenko beam is proposed that is consistent with previous works. More specifically, buildings are represented through equivalent anisotropic beam models in terms of axial, shear and bending cross-sectional stiffnesses, as well as the offset between the axis and the ground surface. Firstly, model predictions are compared with centrifuge results of tunnelling-induced distortions of building models with façade openings. Then, simple beams with varying Young's modulus to shear modulus ratios are analysed. Results detail tunnelling-induced displacements, internal forces, and deformations, as well as bending and diagonal strains of the Timoshenko beams; the way in which both axis-ground offset and shear flexibility level alter the tunnel-structure interaction mechanism was quantified. For damage assessments, an improved approach is proposed to estimate bending and diagonal strains. Finally, to enable practical implementation, design charts that relate both the relative soil-structure stiffness parameters (that account for both bending and shear contributions) and the foundation plan size ratio to the deflection ratio modification factors are given. [ABSTRACT FROM AUTHOR]