D-InSAR monitoring of ground deformation related to the dewatering of construction sites. A case study of Glòries Square, Barcelona

Joan Botey i Bassols,Michele Crosetto,Enric Vàzquez-Suñé,Pierre Gerard,Anna Barra

doi:10.1016/j.enggeo.2021.106041

Abstract

The aim of this paper is to demonstrate how the integration of differential interferometric synthetic aperture radar (D-InSAR) and levelling improves the monitoring of ground deformation phenomena, thereby enabling their complete understanding. The complementarity between D-InSAR and levelling is illustrated through a case study of the construction of a road tunnel beneath Glòries Square, Barcelona; D-InSAR is employed to continuously monitor the works, notably the dewatering of the site. This study focuses primarily on D-InSAR data obtained from the processing of Sentinel-1A data following a persistent scatterer interferometry procedure. The spatial distribution of the deformation and its temporal evolution are analysed with detailed hydrogeological and piezometric data. The magnitude of deformation is discussed using levelling data and an analytical estimation based on the hydromechanical parameters of the ground obtained from a pre-existing hydrogeological numerical model and pumping tests. The D-InSAR results are shown to be essential for identifying the origin of ground deformation and the constraints on its spread. Such observations at the construction site and district (~2 km radius) scales with sub-centimetric deformation are precious contributions of D-InSAR data, whereas levelling offers a more accurate quantification of the deformation, although this remains an open issue to be further investigated. • Differential interferometric SAR as monitoring technique in civil works. • Ground deformation related to the dewatering of construction works. • Hydrogeological interpretation of D-InSAR results. • Complementarity of differential interferometric SAR and levelling.

Highlights

The work of technicians and researchers who play a role in land management is both explicitly and implicitly guided by the concept of risk, which is the product of the probability of a certain phenomenon occurring and the damage that the phenomenon is capable of causing
The aim of this paper is to demonstrate how the integration of differential interferometric synthetic aperture radar (D-InSAR) and levelling improves the monitoring of ground deformation phenomena, thereby enabling their complete understanding
In the presented case study, the deformation is expected a priori to be related to the drawdown caused by the dewatering of the civil works

Summary

Introduction

The work of technicians and researchers who play a role in land management is both explicitly and implicitly guided by the concept of risk, which is the product of the probability of a certain phenomenon occurring and the damage that the phenomenon is capable of causing. A common problem in risk management is the interactions between multiple agents acting on the environment. In dense urban environments, infrastructures are often built below the water table, which requires dewatering during their construction and potentially during their exploitation as well (Pujades et al, 2014b). These operations become increasingly risky, inducing a variety of detrimental phenomena ranging from small magnitudes of settlement, which may or may not be differential depending on the geological context, to sinkholes and col lapses (Clarke and Laefer, 2014; Cheng et al, 2020; Font-Capoet al., 2011; Font-Capoet al., 2015; Haack, 2010; Jurado et al, 2012; Pujades et al, 2012).

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