Investigation on the Tunnel Curvature Effect upon the Ceiling Temperature of Tunnel Fires: A Numerical Simulation

Lu, Kaihua; Xia, Kaihua; Shi, Congling; Yang, Manjiang; Wang, Jie; Ding, Yanming

doi:10.1007/s10694-021-01183-1

Cited by 19 publications

(3 citation statements)

References 33 publications

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“…Their experiments revealed that the fire source's location impacts the ceiling temperature, while increased longitudinal ventilation rates result in a linear decrease in the maximum tunnel temperature. Lu et al [17] used numerical simulations to examine the ceiling temperature distribution in curved tunnels during fires. They observed that temperature decay coefficients increased linearly with the tunnel curvature, with less dependence on fire heat release rates, and introduced a new exponential decay model for predicting longitudinal temperatures in various tunnel curvature situations.…”

Section: Introductionmentioning

confidence: 99%

Fire Hazard Analysis on Different Fire Source Locations in Multi-Segment Converging Tunnel with Structural Beams

Wei,

Tang,

Zhao

et al. 2023

Fire

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To investigate the fire risk in a complex tunnel with varying cross-sections, sloped structures, and dense upper cover beams, this study considered four fire source positions: the immersed tube section, confluence section, highway auxiliary road section, and four-lane sections of the main line. It also considered four beam spacings: 1 m, 1.8 m, 3.6 m, and 7.2 m. The Fire Dynamics Simulation Software FDS was utilized to create a comprehensive tunnel model. The analysis focused on temperature and visibility changes at a 2 m height under a 20 MW fire condition for different fire source positions. These changes were then compared with critical danger values to assess the safety of evacuating personnel within the tunnel. Subsequently, this study proposed corresponding emergency rescue strategies. The findings indicated that when the beam grid spacing exceeded 3.6 m, the upper dense beam gap showed a robust smoke storage capacity, leading to a reduced distance of high-temperature smoke spread. However, this increased smoke storage disrupted the stability of the smoke layer, resulting in a heightened smoke thickness. The location of the ventilation vent at the entrance of the immersed tunnel section caused a non-uniform ventilation flow under the girder, deflecting the smoke front towards the unventilated side and decreasing visibility in the road auxiliary area. In comparison to scenarios without a beam lattice, the presence of a beam lattice in the tunnel amplified fire hazards. When the beam lattice spacing was 3.6 m or greater, the extent of the hazardous environment, which is unfavorable for personnel evacuation, expanded. With the exception of the scenario where the fire source was located in the highway auxiliary roadway, all other conditions surpassed 150 m, which is roughly one-third of the tunnel length. Consequently, more targeted strategies are necessary for effective evacuation and rescue efforts.

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Section: Introductionmentioning

confidence: 99%

Fire Hazard Analysis on Different Fire Source Locations in Multi-Segment Converging Tunnel with Structural Beams

Wei,

Tang,

Zhao

et al. 2023

Fire

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“…1,2 According to statistics, more than 85% of the casualties in tunnel fires are caused by inhalation of toxic smoke caused by suffocation or poisoning. 3 At present, scholars have done a lot of research on tunnel fires, such as the variation of the rule of smoke back-layering length, [4][5][6][7][8][9][10] smoke temperature, [11][12][13][14][15][16] the distribution characteristics of smoke, the critical ventilation velocity in the tunnel, [17][18][19] etc.…”

Section: Introductionmentioning

confidence: 99%

Study on the variation rule of smoke back‐layering length of tunnel ceiling jet induced by strong fire plume

Chen

Zhou

et al. 2022

Fire and Materials

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Tunnel fire is a major research topic in tunnel safety. Because of the tunnel's narrow and enclosed structure, smoke movement plays an important role in the investigation of the tunnel fire. In this paper, the Froude similarity principle is used to study the variation rule of the smoke back-layering length of tunnel ceiling jet induced by strong fire plume with different heat release rates, longitudinal ventilation velocities, and effective heights of fire source analyzed. It is found that the smoke back-layering length of tunnel ceiling jet induced by strong fire plume increases with the increase of effective height of fire source and decreases with the increase of longitudinal ventilation velocity. When the heat release rate is relatively small (Q < 60kW), the smoke back-layering length of the tunnel ceiling jet induced by strong fire plume increases as the heat release rate increases. However, for the larger heat release rate (Q ≥ 60kW), the smoke back-layering length of the tunnel ceiling jet induced by strong fire plume is mainly related to the longitudinal ventilation velocity. Based on Thomas's model and Li's model, by introducing the correction coefficient, correction formulas of the smoke back-layering length of tunnel ceiling jet induced by strong fire plume changing with the effective height of fire source are proposed.

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“…Qu et al [ 22 ] and Lu et al [ 23 ] used the conservation law, the theories of high-temperature gas dynamics, and fluid mechanics to set up the physical and mathematical turbulence flow field model and simulated a tunnel fire and its smoke flow. Lu et al [ 24 ] studied the temperature distribution in curved tunnels using a numerical simulation method, and the results showed that the temperature was slightly higher for a concave wall than a convex wall for the distant positions from the fire source, which was different from that in a straight tunnel. Li et al [ 25 ] carried out 1:10 reduced-scale tests for branched tunnels to investigate the longitudinal fire location effects on thermal smoke temperature distribution beneath the ceiling.…”

Section: Introductionmentioning

confidence: 99%

Analysis on Damage and Mechanical Properties of Ballastless Track in a Tunnel after a Fire

Chen

et al. 2022

Materials

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In order to explore the damage and mechanical properties of ballastless track after a fire, the uniaxial compressive strength, shear strength, peak strain, and elastic modulus changes due to temperature were obtained through uniaxial compressive and shear tests of concrete after exposure to high temperatures. The test results showed that with increases in temperature, the uniaxial compressive strength, shear strength, and elastic modulus of concrete all presented a decreasing trend, while the peak strain had an increasing trend. Then, based on the classical damage theory model and the strength probability distribution function of concrete micro-units, the high-temperature damage constitutive equation for concrete was established, and the compressive stress–strain curve of concrete after exposure to high temperature was reproduced. Finally, using the CFD numerical simulation software, the temperature field of a ballastless track structure in a tunnel during a fire was obtained, and the temperatures at different positions of ballastless track bed were acquired. Combined with the high-temperature damage constitutive equation for concrete deduced from tests and theoretical analysis, the strength and damage values of the ballastless track bed at different positions after a tunnel fire were obtained.

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Investigation on the Tunnel Curvature Effect upon the Ceiling Temperature of Tunnel Fires: A Numerical Simulation

Cited by 19 publications

References 33 publications

Fire Hazard Analysis on Different Fire Source Locations in Multi-Segment Converging Tunnel with Structural Beams

Fire Hazard Analysis on Different Fire Source Locations in Multi-Segment Converging Tunnel with Structural Beams

Study on the variation rule of smoke back‐layering length of tunnel ceiling jet induced by strong fire plume

Analysis on Damage and Mechanical Properties of Ballastless Track in a Tunnel after a Fire

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