Interpretation of an artificial ground freezing field trial at Fori Imperiali in Rome

Abstract

This paper describes a field trial of artificial ground freezing (AGF) carried out in connection with the construction of Line C of Roma underground. AGF was one of the options considered for the temporary stabilisation of the ground during the excavation of Colosseo-Fori Imperiali Station. The field trial aimed at assessing the feasibility of AGF in the complex soil profile and groundwater regime of the subsoil of the historical centre of Roma by establishing the response of the subsoil to the imposed freezing loads, the ability to create a continuous frozen wall, and the associated coolant consumption. The extensive monitoring data were exploited to conduct a detailed analysis of the transient freezing process in the stratified subsoil and used to develop and validate a three-dimensional thermo-hydraulic numerical model. Special attention was given to defining and applying appropriate boundary conditions at the freezing pipes. The paper discusses the main factors affecting the time-dependent freezing process and explores the applicability of simplified two-dimensional models for the Fori Imperiali AGF field trial.

Keywords

Tunnelling / Artificial ground freezing / Numerical modelling / Heat transfer

Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

CRediT authorship contribution statement

Giulia Guida: Writing - review & editing, Writing - original draft, Visualization, Validation, Software, Methodology, Formal analysis, Conceptualization. Arianna Pucci: Software. Eliano Romani: Resources, Investigation. Giulia M.B. Viggiani: Writing - review & editing, Methodology. Francesca Casini: Project administration, Conceptualization.

Declaration of competing interest

Giulia M.B. Viggiani is an editorial board member for Underground Space and was not involved in the editorial review or the decision to publish this article. All authors declare that there are no competing interests.

Acknowledgement

We would like to acknowledge the Regione Lazio, which supported Dr. Giulia Guida’s fixed-term position through POR-FSE 2014/20 - Contributions for the permanence of excellence in the academic world (No. 65629/2020). Ministry of Economic Development supported Dr. Arianna Pucci through the Frozen GeoLab - Proof of Concept project (G.U.n. 283 03/12/2019). Metro C S.c.p.A. provided access to the data. The Master dissertations of Roberta Angelucci and Luca Schillaci were the starting point of this study.

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