Lai Hongpeng, Wang Shuyong, Xie Yongli
School of Highway, Chang'an University, Xi'an 710000, China.
Fujian Communications Planning and Design Institute, Fuzhou 350000, China.
Int J Environ Res Public Health. 2016 Oct 15;13(10):1014. doi: 10.3390/ijerph13101014.
In the New Qidaoliang Tunnel (China), a rear-end collision of two tanker trunks caused a fire. To understand the damage characteristics of the tunnel lining structure, in situ investigation was performed. The results show that the fire in the tunnel induced spallation of tunnel lining concrete covering 856 m³; the length of road surface damage reached 650 m; the sectional area had a maximum 4% increase, and the mechanical and electrical facilities were severely damaged. The maximum area loss happened at the fire spot with maximum observed concrete spallation up to a thickness of 35.4 cm. The strength of vault and side wall concrete near the fire source was significantly reduced. The loss of concrete strength of the side wall near the inner surface of tunnel was larger than that near the surrounding rock. In order to perform back analysis of the effect of thermal load on lining structure, simplified numerical simulation using computational fluid dynamics (CFD) was also performed, repeating the fire scenario. The simulated results showed that from the fire breaking out to the point of becoming steady, the tunnel experienced processes of small-scale warming, swirl around fire, backflow, and longitudinal turbulent flow. The influence range of the tunnel internal temperature on the longitudinal downstream was far greater than on the upstream, while the high temperature upstream and downstream of the transverse fire source mainly centered on the vault or the higher vault waist. The temperature of each part of the tunnel near the fire source had no obvious stratification phenomenon. The temperature of the vault lining upstream and downstream near the fire source was the highest. The numerical simulation is found to be in good agreement with the field observations.
在中国新建的七道梁隧道中，两辆罐车尾部相撞引发火灾。为了解隧道衬砌结构的损伤特性，进行了现场调查。结果表明，隧道火灾致使856立方米的隧道衬砌混凝土发生剥落；路面损坏长度达650米；断面面积最大增加4%，机电设施严重受损。最大面积损失发生在火灾点，观察到的混凝土最大剥落厚度达35.4厘米。火源附近拱顶和侧壁混凝土强度显著降低。隧道内表面附近侧壁混凝土强度损失大于围岩附近。为对热荷载对衬砌结构的影响进行反分析，还采用计算流体动力学（CFD）进行了简化数值模拟，重现火灾场景。模拟结果表明，从火灾发生到火势稳定，隧道经历了小规模升温、火灾周围漩涡、回流和纵向湍流等过程。隧道内部温度对纵向下游的影响范围远大于上游，而横向火源上下游的高温主要集中在拱顶或较高的拱腰处。火源附近隧道各部位温度无明显分层现象。火源附近拱顶衬砌上下游温度最高。数值模拟结果与现场观测结果吻合良好。
