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Sant'Ambrogio di Torino, Italy

Guo X.,Dalian University of Technology | Zhang Q.,Geodata Engineering
Applied Thermal Engineering

A new measure of fire size Q′ has been introduced in longitudinally ventilated tunnel as the ratio of flame height to the height of tunnel. The analysis in this article has shown that Q′ controls both the critical velocity and the maximum ceiling temperature in the tunnel. Before the fire flame reaches tunnel ceiling (Q′ < 1.0), Froude number Fr increases with Q′, which is the typical trend of small tunnel fire. Once the flame height exceeds the height of tunnel (Q′ > 1.0), Fr approaches a constant value. This is also a well-known phenomenon in large tunnel fires. Tunnel ceiling temperature shows the opposite trend. Before the fire flame reaches the ceiling, it increases very slowly with the fire size. Once the flame has hit the ceiling of tunnel, temperature rises rapidly with Q′. The good agreement between the current prediction and three different sets of experimental data has demonstrated that the theory has correctly modelled the relation among the heat release rate of fire, ventilation flow and the height of tunnel. From design point of view, the theoretical maximum of critical velocity for a given tunnel can help to prevent oversized ventilation system. © 2013 Elsevier Ltd. All rights reserved. Source

Guo X.,Dalian University of Technology | Zhang Q.,Geodata Engineering
Tunnelling and Underground Space Technology

A new integral theory for tunnel fire under longitudinal ventilation has been presented. Its solution on critical velocity has been compared with experimental data and the results of CFD simulation from two different computer programs. The exercise of cross examination is not only aimed at further verification of the new theory but also to reveal any problem in all three kinds of data being compared, particularly the pitfalls that may exist in CFD simulation. The comparison has shown that the general agreement among all three kinds of data is satisfactory. Both theoretical and CFD predictions have confirmed the trend of variation for critical velocity versus fire size shown in the experimental data. However the CFD prediction from FDS program for a narrow tunnel has failed to conform to the same trend as that in the theory and experimental data. Considering similar FDS result in comparable condition previously published by another researcher, the authors of the current article believe that CFD simulation results for tunnel fire need to be more closely scrutinized. The simulated result may not only contain numerical error but also go way out of trend and difficult to be physically interpreted. Discrepancy between the current theory and experimental data in some cases is believed due to flame heat loss that has not been accurately predicted by the theory. © 2014 Elsevier Ltd. Source

Moutafis N.I.,National Technical University of Athens | Fornari E.,Geodata Engineering | Nionelli P.,Geodata Engineering | Favata G.,Geodata Engineering | And 2 more authors.
International Journal on Hydropower and Dams

The Minas-San Francisco and La Union cascode hydro scheme is on the Jubones river in the Azuay and El Oro Provinces, in the south of Ecuador, 500 km from Quito. Design alternatives for the underground structures were based on multiple-criteria analysis, taking into account the hydraulic constraints, the detailed dimensioning of the underground openings to ensure the safety of personnel during construction and operation, and a detailed 3D geomechanical model, which facilitated detailed consideration of mitigation measures to potentials risks during construction and operation. Source

Silva M.A.A.P.,Consorcio Andrade Gutierrez Camargo Correa Linha 5 Lote 3 | Goncalves F.L.,Consorcio Andrade Gutierrez Camargo Correa Linha 5 Lote 3 | Aguiar F.L.,Consorcio Andrade Gutierrez Camargo Correa Linha 5 Lote 3 | Aguiar G.,Consorcio Andrade Gutierrez Camargo Correa Linha 5 Lote 3 | And 5 more authors.
Underground - The Way to the Future: Proceedings of the World Tunnel Congress, WTC 2013

The Line 5 Extension is the major government investment for public transport currently in progress in São Paulo/ Brazil. It will connect the São Paulo south area to its central area, connecting the Largo 13 Station in the South to the Line 1 Santa Cruz Station and Line 2 Klabin Station, all in current operation. The whole extension has 11 kilometers of line, including 11 new stations and a new parking yard. This paper will present unique aspects from the first 5 kilometers, a stretch with two 6.9 meter TBM track tunnels, two conventional double track tunnels, three Ventilation and Exit Shafts, as well as the Brooklin Station. Geological and geotechnical aspects will also be presented, including how they were crucial for the major decision concerning TBM choice, design aspects and its optimization. © 2013 Taylor & Francis Group. Source

Grasso P.,Geodata Engineering | Pescara M.,Geodata Engineering | Soldo L.,Geodata Engineering
ITA-AITES World Tunnel Congress 2016, WTC 2016

Risk management in tunneling is more important today than it was a few years ago, considering increasing demands for safety and environmental and socio-economic sustainability, which are now required by citizens, owners, lenders, and insurers. Moreover, our current risk management philosophy should not only address risk avoidance and mitigation, but should also be used as a means of value creation, benefiting the overall project. Given the strategic implications of risk management, the authors intend to present, in this paper, a comprehensive overview of references and experiences from current practice - e.g., what is missing or weak, as well as possible or necessary developments that can have a key role in implementing effective risk management, particularly for a project's design and construction phases. Source

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