火灾后RC及HFRC隧道管片破坏试验研究

为研究火灾后盾构隧道管片的破坏模式,借助火灾试验手段,对钢筋混凝土(RC)及混杂纤维混凝土(HFRC)两种类型的管片在不同工况下的破坏模式进行了研究。根据试验结果,受正弯矩单向加载的钢筋混凝土管片的极限承载力和变形性能均大于混杂纤维混凝土管片。在该工况下,钢筋混凝土管片的破坏模式为弯曲破坏,混杂纤维混凝土管片的破坏模式则为弯曲剪切破坏。而在受负弯矩双向加载的工况下,钢筋混凝土管片为剪切破坏模式,而混杂纤维混凝土管片为受弯破坏模式。由于破坏模式的差别,导致混杂纤维混凝土管片的变形发挥要优于钢筋混凝土管片。基于以上结论,笔者对盾构隧道管片的抗火设计提出了一些相关建议。

Experimental Study on the Post-fire Failure Mode of RC and HFRC Tunnel Segments

This study concerns about failure modes of shield tunnel segments after fire exposure.With the means of fire tests on reinforced concrete (RC) and hybrid fiber reinforced concrete (HFRC) segments,failure modes under different working conditions were studied.According to the testing results,under the condition of positive bending moment uniaxial loading,the ultimate bearing capacity and deformation properties of RC segments were larger than those of HFRC segments.In this condition,the failure mode of RC segments was bending failure,while the failure mode of HFRC segments was shear failure.On the other hand,under the condition of negative bending moment biaxial loading,the failure mode of RC segments was shear failure,while the failure mode of HFRC segments was flexural failure.With regard to the difference of failure modes,the deformation of HFRC segments worked better than RC segments.Based on the conclusions above,some suggestions in fire-proof designs of shield tunnel segment were put forward.