Evaluation of ground freezing data from the Naples subway

Abstract

The method of artificial ground freezing was employed to ensure stability and waterproofing of the platform and escalator tunnels in the Università station of the Naples underground. The paper presents the temperature histories monitored within the ground during the freezing process. Furthermore, the importance of the mineralogical composition of the ground is discussed and it is shown that the temperatures monitored can be interpreted numerically using the ‘Freeze' code, a thermo-hydraulic software developed at the ETH Zurich. The influence of important parameters, such as the spacing between the freeze pipes, the thermal conductivity of the ground and the time–development of cooling temperatures in the freeze pipes, is investigated and critically discussed in order to gain a better understanding of the thermal behaviour of the ground during artificial freezing with liquid nitrogen. ‘Freeze' software is a powerful tool for analysing field data for cases involving non-constant temperatures within freeze pipes.

Artificial Ground Freezing to excavate a tunnel in sandy soil. Measurements and back analysis

“…Colombo (2010) studied the problem of heat propagation, comparing analytical solutions and numerical analyses obtained via FEM. Papakonstantinou et al (2012) with a thermo-hydraulic coupling, numerically examined the field of temperatures monitored within the ground during a freezing process. The thermo-hydro-mechanical interaction induced by the Artificial Ground Freezing has been studied by Casini et al (2013) using a constitutive model encompassing frozen and unfrozen behavior.…”

Case Study of Heat Transfer during Artificial Ground Freezing with Groundwater Flow

“…With its good water barrier and non-pollution characteristics, the artificial ground freezing (AGF) method is widespread in environmental engineering (e.g., excavation of pollutants) [1,2], mining engineering (e.g., mine shafts construction), and especially in underground engineering (e.g., subsea tunnel and urban subway construction) [3][4][5][6]. The basic principle of this method is to circulate a fluid refrigerant (ca.…”

Artificial ground freezing of a volcanic ash: laboratory tests and modelling

“…Both analytical and finite-element approaches were adopted to analyse realistic layouts of freezing tubes similar to those used during construction of Napoli underground, and the results were compared with the experimental data. Papakonstantinou et al (2012) examined the temperature monitored within the ground during the freezing process numerically and took into account the thermo-hydraulic coupling. The influence of a number of parameters, including the spacing between the freeze pipes and the thermal conductivity of the ground, was investigated to gain an understanding of the thermal behaviour of the ground during activation of artificial freezing with nitrogen.…”