Experimental research on fire resistance of the reduced scale immersed tunnel with fire in both traffic tubes
Experimental research on fire resistance of the reduced scale immersed tunnel with fire in both traffic tubes
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DOI：
10.1016/j.tust.2022.104922
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发表时间：
2022-12-27
影响因子：
6.9
通讯作者：
Qi, Jianquan
中科院分区：
文献类型：
--
作者：
Dong, Yuli;Duan, Jintao;Qi, Jianquan
为研究混凝土沉管隧道的火灾性能，建立了大比例的沉管隧道模型，同时搭建了加载装置和两台火灾试验炉。火灾测试考虑了极端火灾条件。在没有防火保护的情况下，在隧道的两个管道中同时进行火灾测试。隧道内，火灾最高温度超过1300摄氏度。在使用荷载作用下，对隧道进行了245 min的火灾加热和360 min的通风降温试验，记录了隧道的温度、变形、开裂、剥落等行为。试验数据提供了火灾下隧道结构损伤和结构变形的记录。火灾下隧道混凝土剥落几乎达到100%，混凝土剥落最大深度达到142.2 mm，隧道内部钢筋暴露在火中，部分钢筋熔化。中间的墙壁遭受了最严重的破坏，这是最危险的隧道在火灾中。但隧道的变形主要是由各构件的轴向变形引起的，而且很小。试验结果表明，该隧道在火灾下的承载力是足够的，但隧道的混凝土开裂非常严重。在火灾试验过程中，受混凝土热胀冷缩的影响，隧道非受热面和受热面交替开裂，且开裂位置重叠，可能导致隧道内部产生贯通性裂缝。在火灾下沉管隧道有足够承载力的情况下，混凝土开裂仍会造成灾害或降低沉管隧道的耐久性。在沉管隧道的抗火设计中，应采取措施抑制混凝土开裂，提高中墙在火灾作用下的抗弯承载力。
In order to investigate the fire performance of concrete immersed tunnels, a large-scale model of an immersed tunnel was constructed, loading devices and two fire test furnaces were built at the same time. The fire test considered an extreme fire condition. Without fire protection, the fire test was carried out in both tubes of the tunnel at the same time. In the tunnel, the maximum temperature of fire exceeded 1300 degrees C. Under the service load, the tunnel was heated by fire for 245 min, and then the tunnel was cooled by ventilation for 360 min. During the fire test, the temperatures, deformations, cracking, spalling, and other behaviors of the tunnel were recorded. The test data provided the record of the structural damage and structural deformations of the tunnel under fire. The concrete spalling of the tunnel under fire was almost 100 %, and the maximum depth of the concrete spalling reached 142.2 mm. The inner rebars of the tunnel were exposed to fire, and some rebars melted. The mid wall suffered the severest damage, and it was the most dangerous of the tunnel under fire. However, the deformation of the tunnel was mainly caused by the axial deformation of each component, and it was very small. The test results showed that the bearing capacity of the tunnel under fire was sufficient, but the concrete cracking of the tunnel was very severe. During the fire test, affected by the thermal expansion and contraction of concrete, the unheated side and heated side of the tunnel alternately cracked, and the crack positions overlapped, which might cause through cracks inside the tunnel. In the case of sufficient bearing capacity of immersed tunnels under fire, concrete cracking can still cause disaster or reduce the durability of immersed tunnels. In the fire resistance design of immersed tunnels, measures should be taken to restrain the concrete cracking and improve the flexural bearing capacity of the mid wall under fire.