摘要
隧道火灾对人员生命产生威胁的同时也会对隧道结构安全产生影响。首先,根据火灾时的实际情况建立了地铁区间隧道火灾烟气三维温度场。其次,考虑隧道壁面与高温烟气的热对流、热传导、衬砌材料传热性能的非线性以及衬砌混凝土爆裂建立了火灾时衬砌温度场求解的基本方程与求解方法,对比试验结果验证了所提方法的准确性。再次,结合求解得到的三维温度场,考虑衬砌材料热力学性能为温度的非线性函数,使用有限单元法对火灾时衬砌内部应力进行了求解。最后,按照弹性失效准测以及三轴受力情况,对衬砌破坏的形态及范围进行了分析。研究发现:衬砌破坏主要由内侧混凝土压碎引起;受火7200 s后,沿行车方向16 m,厚度方向12 cm,拱顶向下112°范围内衬砌受压超过其抗压强度;管片主筋处,1800 s内其受力均小于其强度;管片破坏形态主要为片状劈裂;螺栓在火灾后期会出现抗剪强度不足,主要范围分布在对拱顶向两侧37°范围内。
Tunnel fires pose a threat to human life and have an impact on the structural safety of tunnels.First,this paper establishes a 3D temperature field of the fire smoke according to the actual fire conditions in a metro running tunnel.Then,the basic equations and solutions to the lining temperature field during the fire are derived by taking into consideration the thermal convection,heat conduction between the tunnel wall and heating smoke,the nonlinearity of heat transfer properties of the lining materials as well as the concrete spalling,The accuracy of the proposed method is verified by comparing with the test results.Furthermore,combined with the 3D temperature field obtained from the solution,the stress in the lining during the fire is solved by the finite element method under considering the lining material’s thermodynamic properties as the non-linear functions to the temperature.Finally,the lining failure patterns and ranges are analyzed according to the elastic failure criterion and the triaxial stress conditions.The study results show that the lining failure is mainly caused by the compressive crushing of the inner concrete;after 7200 s of the fire,the compressive stress of the lining exceeds the compressive strength within the range of 16 m along the driving direction,12 cm thickness of concrete and 112°from the vault to the sidewall;at the depth of main reinforcements of the lining segment,the concrete stress is less than the strength within 1800 s;the failure pattern of the segment is mainly flake splitting;and the bolts have insufficient shear strength in the late stage of the fire,within the range of 37°at both sides of the vault.
作者
韩兴博
赵伟封
HAN Xingbo;ZHAO Weifeng(School of Highway,Chang′an University,Xi′an 710064;Engineering Research Center for Large Highway Structure Safety of Ministry of Education,Chang'an University,Xi′an 710064)
出处
《现代隧道技术》
CSCD
北大核心
2021年第3期33-42,共10页
Modern Tunnelling Technology
基金
中国博士后科学基金(2020M683398)
长安大学中央高校基本科研业务费专项资金(300102210124)。
关键词
衬砌
火灾
热力耦合
破坏规律
破坏形式
Lining
Fire
Thermal coupling
Failure law
Failure pattern
