负荷度对盾构隧道管片火灾下力学性能影响

Effect of Load Bearing Proportion on Mechanical Properties of Shield Tunnel Segments in Fire

针对不同边界条件下的地铁管片建立了热力耦合数值模型,采用顺序耦合热-应力分析方法对不同负荷度下衬砌管片在高温下的变形及内力进行了分析,并基于火灾试验数据进行了验证。研究表明,负荷度是影响管片在火灾高温下变形特性的关键因素。负荷度越大,管片跨中位移在升温阶段发展越充分,下缘混凝土的极限压应力越小。支座边界条件不同时,衬砌管片变形受高温影响的程度也不相同。当衬砌管片两端的水平位移被约束时,由于在升温过程中衬砌管片产生不可忽略的变形,支座反力先增大后减小,最后持续增大直至升温结束。

A thermo-mechanical coupling numerical model is established for the metro segments under different boundary conditions, and the deformation and internal force of the lining segments at different loads and high temperatures are analyzed by adopting the sequential coupled thermo-stress analysis method. The model was verified by fire test data. Loading bear proportion is a key factor affecting deformation characteristics of segments at elevated temperatures. When the load increases, the midspan displacement of segments develops more quickly during the heating stage, while the ultimate compressive stress of the concrete at the lower edge decreases. For different boundary conditions of support, the lining segments also have different mechanical behaviors affected by elevated temperatures. When the horizontal displacements at both ends of the lining segments are constrained, due to the non-negligible deformation of the lining segments during the heating process, the bearing reaction force first increases, then decreases, and finally continues to increase until the end of heating.