钢壳混凝土管节高温破坏机制及防火保护技术研究  

Study on failure mechanism under high temperature conditions and fire protection technology of compartment steel-concrete-steel composite structure

作　　者：蒋树屏 张丹丹[1] 胡学兵 曹鹏[2] JIANG Shuping;ZHANG Dandan;HU Xuebing;CAO Peng(School of Civil Engineering,Chongqing Jiaotong University,Chongqing 400074,China;China Merchants Chongqing Transportation Research and Design Institute Co.,Ltd.,Chongqing 400067,China)

机构地区：[1]重庆交通大学土木工程学院,重庆400074 [2]招商局重庆交通科研设计院有限公司,重庆400067

出　　处：《铁道科学与工程学报》2023年第12期4655-4666,共12页Journal of Railway Science and Engineering

基　　金：国家重点研发计划资助项目(2021YFC3002000);国家自然科学基金资助项目(52127814);重庆市自然科学基金资助项目(cstc2021jcyj-msxmX0591)。

摘　　要：钢壳混凝土组合结构是未来巨型沉管隧道的发展方向,但其耐火性能基础研究不足,结构防火设计在方案确定、参数选择等方面缺乏依据。首先通过开展热-力耦合作用下大比例尺物理模型试验,揭示钢壳混凝土管节火灾高温破坏机制,论证结构防火保护的必要性,进而提出钢壳混凝土管节防火保护方案,并通过足尺试验对方案的有效性与可靠性进行验证。研究结果表明:1)火灾高温下管节结构内部温度分布不均匀,竖直方向、水平方向存在的温度梯度在结构内部产生热应力。2)热-力耦合作用下钢壳混凝土管节宏观损伤明显,主要表现为结构变形、表面裂纹产生与扩展、钢材屈服与局部混凝土颜色改变,且荷载越大损伤越严重,结构耐火极限越短。3)钢壳混凝土组合结构变形与火灾温度密切相关,升温阶段位移随温度的升高而增大,恒温阶段位移基本保持恒定,降温阶段位移逐渐恢复。4)结构内部损伤情况与荷载密切相关,当荷载较低时结构变形较小且随火灾温度的降低有所恢复,部分变形不可逆;当荷载较高时,结构在10min左右发生破坏,整个过程呈脆性破坏模式。5)厚度为22.0mm以上的硅酸钙防火板能够有效减少热量向结构传递,使钢壳温度低于临界温度;防火板保护下,受火后的结构表面不存在明显表观损伤;防火板在整个受火过程中结构完整。钢壳混凝土管节防火板设计方案安全可靠。Compartment steel-concrete-steel(CSCS)composite structures are the future development direction for large-scale submerged tunnel construction.However,there is insufficient foundational research on the structure fire resistance performance,leading to a lack of basis for structural fire protection design in scheme determination and parameter selection.By conducting large-scale physical model tests under thermal-mechanical coupling,the fire-induced high-temperature failure mechanism of steel-concrete composite tunnel segments was revealed.The necessity of structural fire protection was demonstrated,followed by proposing a fire protection scheme for steel-concrete composite tunnel segments.The effectiveness and reliability of the scheme were then verified through full-scale experiments.The findings indicate:(1)An uneven temperature distribution in tunnel elements occurs in tunnel fire,and vertical and horizontal temperature gradients result in thermal stress in the structure.(2)Under thermal-mechanical coupling,macro damage to the CSCS composite structure is evident and mostly manifests as structural deformation,surface crack creation and propagation,steel yield,and local concrete color change.The damage is more severe and the fire resistance limit is reduced as the load increases.(3)Deformation of steel-concrete composite structures correlates closely with fire temperatures,whereas displacement increases with temperature during the heating stage,remains relatively constant during the constant-temperature stage,and gradually recovers during the cooling stage.(4)The load has a direct impact on internal structural deterioration.Low loads result in minimal structural deformation,some of which recovers when fire temperature falls,but some of which is irreversible.When the load is high,the structure is destroyed in about 10 minutes,exhibiting brittle failure mode throughout the entire process.(5)Calcium silicate fire-proof boards can effectively reduce heat transfer to the structure when the board thickness is over 22.0 m

关 键 词：隧道工程 高温破坏 物理模型试验 防火保护技术 沉管隧道 

分 类 号：U451[建筑科学—桥梁与隧道工程]