Tunneling in an urban critical area - a case study

• Type: Article in International Conference Proceedings Book
• Date: 2007

Authors

Jorge Machado de Carvalho (Author) FEUP; Abílio Cavalheiro (Author) FEUP; Pedro Teixeira (Author) FEUP

Conference proceedings International

Title: Underground space the 4th Dimension of Metropolises (Vol. 2)

33th ITA-AITES World Tunnel Congress

Prague - Czech Republic, 5-10 May 2007

Indexing

ISI Web of Science

Scopus

Scientific classification

CORDIS: Natural sciences > Environmental science > Earth science > Geophysical sciences

Other information

Abstract (EN): A 700m road tunnel crossing very heterogeneous granite formations within a critical area of the city of Porto, Portugal, in which around 400m were excavated below groundwater according to NATM principles, has been open to public use in 2005. The average excavated section area is 100m2 with a cover varying between 2,7m and 21m. The concerned area is quite challenging from a geological/geotechnical point of view ¿ very heterogeneous Porto granite rock mass overlaid by residual soil ¿ as well as from a technical/environmental and social point of view ¿ intense traffic, densely constructed and under construction area having some problematic old nearby buildings with delicate foundations. The question of whether or not explosives should be used in such an environment has been a very controversial issue. Following various geotechnical, geophysical, vibration surveys, reports and feasibility studies, the tunnel has been successfully excavated using mainly blasting techniques and, whenever necessary, mechanized means. During the tunnel excavation a comprehensive seismic vibration monitoring survey took place aiming at preventing damage risks as well as optimizing subsequent blasting diagrams. The present report, following a brief summary of some project key issues regarding namely the final feasibility study, adjusted in-situ strategies during the excavation works, monitoring procedures and safety measures, presents seismic vibration monitoring data treatment procedures and an example of the promising preliminary results aiming at improving the geological/geotechnical model inference along the tunnel alignment.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 7