Location
Arlington, Virginia
Date
14 Aug 2008, 2:15pm - 4:00pm
Abstract
Within the Metro Line 1 extension project in Napoli (Italy), the service tunnel at Toledo station was one of the most critical sections of the project. The 13m wide, 17m high, 40m long tunnel is located downtown under a deeply urbanized area. It was excavated starting from an access shaft and from this tunnel four platform tunnels are under excavation. The geology of the site is characterized by volcanic soils: loose pozzolana silty sand and tuff. The underground works were carried out under a hydrostatic head of 27 m. In order to allow a safe and substantially dry excavation, soil/rock improvements were carried out by a combination of two different methods: cement and chemical grouting at the sides and invert (in tuff) and Artificial Ground Freezing (AGF) at the crown (in pozzolana). The treatments were carried out both from a drift located approximately 10 m above the crown and from the access shaft. The grouting process was controlled and monitored by a computerized system. To check the development and the efficacy of the freezing process, suitable sensors and automatic data acquisition and recording systems were installed. The variation of the temperature within the soil and the cooling fluids were monitored during the entire freezing operation.
Department(s)
Civil, Architectural and Environmental Engineering
Meeting Name
6th Conference of the International Conference on Case Histories in Geotechnical Engineering
Publisher
Missouri University of Science and Technology
Document Version
Final Version
Rights
© 2008 Missouri University of Science and Technology, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
Document Type
Article - Conference proceedings
File Type
text
Language
English
Recommended Citation
Manassero, Vittorio; Di Salvo, Giuseppe; Giannelli, Fabio; and Colombo, Giuseppe, "A Combination of Artificial Ground Freezing and Grouting for the Excavation of a Large Size Tunnel Below Groundwater" (2008). International Conference on Case Histories in Geotechnical Engineering. 2.
https://scholarsmine.mst.edu/icchge/6icchge/session07/2
A Combination of Artificial Ground Freezing and Grouting for the Excavation of a Large Size Tunnel Below Groundwater
Arlington, Virginia
Within the Metro Line 1 extension project in Napoli (Italy), the service tunnel at Toledo station was one of the most critical sections of the project. The 13m wide, 17m high, 40m long tunnel is located downtown under a deeply urbanized area. It was excavated starting from an access shaft and from this tunnel four platform tunnels are under excavation. The geology of the site is characterized by volcanic soils: loose pozzolana silty sand and tuff. The underground works were carried out under a hydrostatic head of 27 m. In order to allow a safe and substantially dry excavation, soil/rock improvements were carried out by a combination of two different methods: cement and chemical grouting at the sides and invert (in tuff) and Artificial Ground Freezing (AGF) at the crown (in pozzolana). The treatments were carried out both from a drift located approximately 10 m above the crown and from the access shaft. The grouting process was controlled and monitored by a computerized system. To check the development and the efficacy of the freezing process, suitable sensors and automatic data acquisition and recording systems were installed. The variation of the temperature within the soil and the cooling fluids were monitored during the entire freezing operation.
