Affiliation:
1. Lombardi SA, 6512 Bellinzona-Giubiasco, Switzerland
2. Future Generation JV, Cooma NSW 2630, Australia
3. Webuild S.p.A., 00187 Roma, Italy
Abstract
This paper refers to experiments developed on the deep tunnels design of the Snowy 2.0 pumped-storage hydroelectric project in NSW, Australia. The 27 km long waterway and the power station complex are about 800 m below ground, and are in a complex tectonic and lithological setting. Long-term temperature monitoring in boreholes has been used to infer an empirical thermal model along the deep tunnels, which is presented as an example of input data for the ventilation design during construction, and for durability design during operation. An innovative aspect of this paper is related to the graphical interpretative method of borehole temperature logs that is proposed to infer downward or upward groundwater flows and predict the hydrogeological behaviour of fractured and faulted zones that cross the tunnel alignment. A large campaign of thermal acquisition in boreholes, using an acoustic televiewer probe, identified local anomalies of the geothermal gradient, which were correlated to permeability and pressure data measured in the boreholes, to identify zones of greater permeability that intersect the tunnels. Furthermore, the application of thermal measurements during tunnel excavation is proposed as an additional tool for the prediction of water inflow or identification of zones to be pre-grouted and/or drained.
Thematic collection:
This article is part of the Leading to Innovative Engineering Geology Practices collection available at:
https://www.lyellcollection.org/topic/collections/leading-to-innovative-engineering-geology-practices
Publisher
Geological Society of London
Subject
Earth and Planetary Sciences (miscellaneous),Geology,Geotechnical Engineering and Engineering Geology
Reference8 articles.
1. Bamforth, P.B. 2018. Control of Cracking Caused by Restrained Deformation in Concrete. CIRIA-C766 Guide. CIRIA, London.
2. Baynes F.J. and Parry S. 2022. Guidelines for the development and application of engineering geological models on projects. International Association for Engineering Geology and the Environment (IAEG) Commission 25 Occasional Publication 1.
3. Linee guida per la gestione sostenibile delle venute d'acqua e del calore geotermico nelle gallerie;Dematteis A.;Italian Journal of Groundwater,2020
4. Importance of Insulation at the Bottom of Mass Concrete Placed on Soil with High Groundwater
5. Geological prognosis ahead of a tunnel face