An approach for the design of dewatering systems: the case of an excavation for the construction of the assembly shaft of a tunnel boring machine

Robust approaches are needed for designing efficient dewatering systems of deep excavations below the water table to avoid unforeseen incidents (e.g., bottom instabilities in deep excavations and flooding, among others). This paper proposes a methodology, which integrates existing experiences, that was adopted to design the dewatering system of an excavation in the city of Barcelona (Spain). The approach consists of combining: (i) detailed geological and hydrogeological characterizations, (ii) numerical modelling for parameter estimation and drawdown predictions, and (iii) analytical assessment for stability evaluation and soil deformation predictions. The idea is that by combining a set of relatively easy to apply methods, it is possible to successfully solve a complex and risky problem. The methodology allows designing efficient dewatering systems, increasing safety and mitigating potential impacts of groundwater pumping. The most significant conclusion is that the most important step of the proposed approach is the hydrogeological characterization because it allows building realistic and representative numerical models to address most of the challenges associated to dewatering.

This research has been supported by the grant CEX2018-000794-S funded by MCIU/AEI/ 10.13039/501100011033. EP gratefully acknowledges the support received from MCIU/AEI /10.13039/501100011033/ and FEDER ?one way to make Europe? through the grant PID2021-128995OA-I00, MICIU/AEI/10.13039/501100011033 and European Union NextGenerationEU/PRTR through the grant CNS2023-144051 and MICIU/AEI /10.13039/501100011033 European Union through the grant PCI2024-153452. The authors would like to acknowledge ADIF (Administration), SACYR (construction company) and INTECSA-INARSA (technical assistance), for their support throughout the hydrogeological monitoring of the civil works. The authors were appointed by ADIF as external advisors during the construction of the tunnel. The preliminary results of this article were presented in the General Assembly of the European Geosciences Union in 2020. The abstract containing the information of this presentation can be found at https://doi.org/10.5194/egusphere-egu2020-21729. Funding Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature.

Peer reviewed