Ferrado, F.L.; Escalante, M.R.; Rougier, V.C. Numerical simulation of the three-edge bearing test of steel fiber reinforced concrete pipes. Mecánica Comput. 2016, 34, 2329–2341. [ Google Scholar] In the past few years, a series of fire tests in cable tunnels have increased significantly after deadly tunnel fires in Europe. Unlike small-scale tests [ 11] and large-scale tests (such as those conducted in Zwenberg (Austria), Ofenegg(Switzerland), or Finland [ 12]), the Memorial tunnel experimental test showed that it was consistent with the experimental measurement results in the far field of the fire source [ 13]. However, for the length of near fire source area, the calculation is not accurate. Fan [ 14] conducted experimental research in a 1:20 model tunnel, studied the flame length integral model considering the influence of tunnel section and ventilation velocity under large HRR near the fire source, and proposed a dimensionless ventilation velocity form considering the hydraulic diameter of the tunnel. Through a series of fire experiments, Jiang [ 15] studied the phenomenon of the central smoke exhaust system of the tunnel through a series of fire experiments, and measured and analyzed the height, temperature and flow rate of the smoke layer below the smoke vent. In conclusion, in previous studies, CFD simulation method can better analyze the motion law of fluid [ 16– 18]. The phases of work that were meticulously planned, using equipment and platforms especially designed by AMCO/Foulston Forge and Keltbray for the Severn Tunnel, were as follows: In contrast, hiding wires without cutting the wall simply means using plastic rails, and covers or hiding them behind furniture or under the carpet. Vauquelin O, Wu Y. Influence of tunnel width on longitudinal smoke control. Fire Safety Journal, 2006, 41(6): 420–426.

Although this might seem obvious, the number of input and output locations will affect how you conceal your cords. Ma, B.S. The Science of Trenchless Engineering; China Communications Press: Beijing, China, 2008. [ Google Scholar] Hochtief has been contracted to design and supply the cable tunnel, one 400kV cable circuit and one 132kV cable circuit. They will also create headhouses for each end of the tunnel, which includes cable sealing end compounds and the associated mechanical, electrical, instrumentation control and automation systems. Fix 1,700 vertical drop tubes weighing 45 to 60kg, setting them high then lowering into final position; Once the AMCO work team had become familiar with the process of installing the ATF cable, they were achieving 800 metres in a 10- hour shift, a significant achievement.Ji J, Bi Y, Venkatasubbaiah K, et al. Influence of aspect ratio of tunnel on smoke temperature distribution under ceiling in near field of fire source[J]. Applied Thermal Engineering, 2016, 106: 1094–1102. Legrand L, Blanpain O, Buyle-Bodin F. Promoting the urban utilities tunnel technique using a decision-making approach[J]. Tunnelling and Underground Space Technology, 2004, 19(1): 79–83. When the height of the fire source is 0 m, the maximum temperature below the ceiling 2.0 m upstream of the fire source is about 34°C, which is higher than the maximum temperature 0.1 m below the ceiling. When the fire source height is 0 m, the maximum temperature below the ceiling reaches 148 s, which is earlier than 205s when the fire source height is 0.1 m, and the maximum temperature below the ceiling reaches 34.6°C.

Fig 6. Temperature change below the ceiling of the cable compartment in the utility tunnel at 1, 4, 5 and 6 at a distance of 0.5 m from the fire source. National Grid has begun work on two other VIP schemes in Dorset and the Peak District and is planning another in the Cotswolds. Colella F, Rein G, Verda V, et al. Multiscale modeling of transient flows from fire and ventilation in long tunnels. Computers & Fluids, 2011, 51(1): 16–29.Moore, I.D. Buried pipes and culverts. In Geotechnical and Geo-Environmental Engineering Handbook; Springer: Boston, MA, USA, 2001; pp. 541–567. [ Google Scholar] With the rapid development of social production demand and the increase of urban population, the fire in cable compartment is becoming more and more serious. The continuous application and further development of urban underground space has become an inevitable trend. In case of fire in the utility tunnel, it is very dangerous [ 1]. In case of fire in the cable compartment, the smoke is difficult to spread vertically, and can only be discharged from the vents at both ends [ 2]. Therefore, smoke tends to propagate along the longitudinal direction of the cable compartment. Usually, a small fire in a cable compartment can lead to a huge disaster [ 3]. In case of fire, the temperature will change with the change of ventilation velocity and heat release rate (HRR), and the temperature distribution will also change with the passage of time [ 4].

In cases 3 and 9. When the height of the fire source is 0 m, the maximum temperature below the ceiling 0.5 m away from the fire source is 69.2°C, which is higher than 42.9°C when the height of the fire source is 0.1 m. When the fire source height is 0 m, the maximum temperature below the ceiling reaches 69.2°C and the duration is 110 s. When the fire source height is 0.1 m, the maximum temperature below the ceiling reaches 42.9°C and the duration is 170 s. The work that followed had to be planned like a military operation. The devil was in the detail and one minor flaw in the plan would jeopardise the whole process. Meetings with main suppliers AMCO and Keltbray were held daily and, as pointed out by both Dan and John, you could not distinguish one company from another as everyone was working as one team. It was an essential requirement if the work was going to be completed successfully and in time. They were both keen to point out that, in partnership with principal contractor ABC Electrification and key suppliers AMCO, Keltbray, Arup and Furrer+Frey, Network Rail has been able to source about 75 per cent of the team from Wales. He explained that many of the Severn Tunnel engineers have been recruited from former steel and mining industries, while the team also includes a significant number of former armed forces personnel. Zhu, Z.; Ma, B.; Zeng, Z.; Gong, C.; Mei, Z.; Hu, J.; Zhang, P. Discussion on the Defects and Its Inspection and Evaluation Methods for Power Cable Tunnels. Chin. J. Undergr. Space Eng. 2019, 15, 311–318. (In Chinese) [ Google Scholar]

Funding

Within cable transit tunnels, Durasteel systems can be used to provide transverse barriers, inclusive of access doorways and penetration sealing systems, this prevent fire travelling along the cable ways. The Durasteel barriers can also be constructed so as to separate tunnels into two or more distinct compartments, thus further reducing the risk of losing important services to fire. The Durasteel services protection system, combined with the fire stopping and penetration seal systems, offer the end user a wide range of design possibilities. Ma, B.S. Trenchless Pipeline Rehabilitation and Renewal Technology; China Communications Press: Beijing, China, 2014. [ Google Scholar] GB 50010-2010; Code for Design of Concrete Structures. Ministry of Housing and Urban-Rural Development of the People’s Republic of China (MOHURD): Beijing, China, 2010.

The reopening of the tunnel was a critical milestone in the project to deliver electric trains for passengers in South Wales. As well as improved journeys, economists expect electrification of the line between South Wales and London to deliver the economic boost for South Wales that will result from better connectivity to London, a critical factor for attracting investment for the electrification of the route in the first place.National Grid’s Snowdonia Tunnel, which will house pipelines, communication and powerlines, is set to be built by Hochtief. Riahi, E. Evaluation of Structural Capacity of Epoxy-Coated Concrete Pipes and Its Interaction with Soil; University of Texas Arlington: Arlington, TX, USA, 2016. [ Google Scholar] Li, Q.; Kuang, Y.; Guo, W. CDP model parameters calculation and value method verification. J. Zhengzhou Univ. 2021, 42, 43–48. (In Chinese) [ Google Scholar]