| Tunnelling
processes that must be carried out during the construction phase. Several issues also need to be addressed in a comprehensive investigation for the next stage, including but not limited to welding times, construction costs, construction schedule, logistic processes, and risk analysis.
Fire experiments
In their study published in the Journal of Safety Science and Resilience, Liu et al have carried out full-scale fire experiments at a hydropower station to investigate smoke propagation during tunnel construction.
In general, full-scale experiments model real smoke
propagation scenarios and actual smoke development parameters, largely supporting the optimisation of smoke exhaust and emergency response. However, because the underground space of a hydropower station is composed of different types of caverns, the authors claim that current full-scale experiments in areas such as the main power houses and conjunction areas have not yet adequately presented complete fire scenarios and fire propagation processes in hydropower stations. Focusing on this gap, they built full-scale fire scenarios in an access tunnel, which is representative of traffic, construction, and tailrace tunnels, and corridors that occupy most of the underground space of a hydropower station. The distributed temperature in the tunnel was
measured for real-time recording of the smoke propagation process, combined with on-site observations. The flame height of the diesel pool fire, smoke temperature evolution and distribution, and smoke stratification and descent were analysed, and these results could provide on-site fire scenarios and data support for smoke control design and fire emergency response plans in hydropower stations.
Indian TBM In other news, TERRATEC has announced that its
Ø9.86m Hard Rock Double Shield TBM has made significant progress at the Vishnugad-Pipalkoti Hydropower Project in India, successfully excavating 431m in January 2024. The TBM is the largest double shield machine in the Indian Himalayan Region and is currently working for
Hindustan Construction Co, the primary contractor for this project. Specifically designed for the construction of a crucial low-pressure13km long head race tunnel, the TBM’s cutterhead boasts 19’’ disc cutters and twelve large bucket openings, facilitating excavation through expected hard rock with its 4200kW electric main drive delivering a torque exceeding 22,000kNm. As the TBM advances, universal reinforced concrete lining rings, 1500mm wide and 350mm thick, are installed, each comprising five segments plus a key. TERRATEC is also providing its Continuously Advancing Tunnel Conveyor for the project which is capable of handling the various materials extracted by the TBM, expected to vary from sandy gravel to boulders. Situated in Uttarakhand state, this 444MW run- of-river scheme incorporates construction of a 65m high diversion dam across the Alaknanda River and a 3.63Mm3
reservoir. A diversion/spill tunnel, intake
tunnels, underground sedimentation chambers, a headrace tunnel, a surge shaft, pressure shafts, and penstocks, along with two separate underground caverns for turbine and transformer installations, constitute the water conductor system.
Multipurpose tunnels Research undertaken by the Tunnelling Institute of
Pakistan and the University of Huston in the US has proposed the innovative use of an existing road tunnel for water conveyance and power generation. Several road tunnels have recently been built in Pakistan’s northern region, near mountain peaks and bodies of water, and discussion focused on the feasibility of using an existing road tunnel on a high-speed, controlled excess motorway for multipurpose use by taking advantage of natural terrain features. The hybrid tunnel will result in significant cost savings compared to constructing a tunnel for a hydroelectric facility and in addition, the outflowing water can be used for irrigation of agricultural fields. The proposed site used in the study was the 1.3km
long Tunnel No. 1 on the Swat Motorway, located close to the Swat River in Pakistan. The authors say that such measures will help the country which has been facing energy shortages for the past two decades and currently has a shortfall of over 5000MW.
Left: Swat River in Pakistan. Research has looked at the feasibility of using an existing road tunnel in this region for multipurpose water transfer and power generation purposes
References
del Río, D.A.; Caballero, J.A.; Muñoz, J.T.; Parra-Rodriguez, N.C; Nieto-Londoño, C.; Vásquez, R.E.; Escudero-Atehortúa, A. Design of a Self-Supporting Liner for the Renovation of a Headrace Tunnel at Chivor Hydropower Project. Water 2023, 15, 409. https//doi. org/10.3390/w15030409
Study on smoke propagation in tunnel construction of a hydropower station: A full-scale fire experiment by Chang Liu, Huihang Cheng, Wenjun Nie, Senlin Jiang, Junfeng Chen, Peng Lin, Maohua Zhong. Journal of Safety Science and Resilience 4 (2023) 188–202
Expanding Underground Knowledge and Passion to Make a Positive Impact on the World – Anagnostou, Benardos & Marinos (Eds) © 2023 The Author(s), ISBN 978-1-003-34803-0
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