火灾高温下盾构隧道衬砌结构热力耦合模型试验

为研究火灾高温下盾构隧道衬砌结构的热力耦合行为，利用自主研制的温度加载设备和衬砌管环外压加载设备，分别设计并开展整环衬砌结构的无外压受热模型试验和热力耦合模型试验。试验使用不考虑接头效应的钢纤维混凝土匀质管片。首先，介绍2种试验设备的原理、主要构造和各类参数；在此基础上，针对模型试验过程进行细致的说明。然后，通过对衬砌管片结构形式的分析确定试验的火灾加载工况；详尽描述不同试验的相关结果，重点分析衬砌结构内表面各处温度场的变化过程、分布情况、管片的变形结果及破坏模式。研究结果表明：温度加载设备和衬砌管环外压加载设备能够较好的满足整环衬砌热力耦合研究的模型试验要求；试验初期底部管片的升温速率相对顶部管片有所滞后，但各部分间的温差数值随加热的持续进行会逐渐减小，衬砌结构内部能够形成稳定的温度场；无外力作用下匀质管片的破坏形式表现为沿幅宽方向的贯穿裂缝，各管片结构的裂缝发展路径存在差异；衬砌管片由于外压作用产生的压应变随温度的升高而减小；外压荷载对衬砌结构在高温下产生的膨胀变形存在抑制效果。研究结果可为盾构隧道整环衬砌结构热力耦合研究的进一步发展提供参考。

Model Test on Thermomechanical Coupling of Shield Tunnel Lining Under High Fire Temperature

To study the thermomechanical coupling behavior of a shield tunnel lining at high temperatures, a heating model test with no external pressure and thermomechanical model test of a whole ring lining were designed and conducted using self-developed temperature-loading equipment and an external pressure loading device. The homogeneous segment composed of steel fiber reinforced concrete and without considering the joint effect was the subject of the test. First, the principles, main structure, and various parameters of the two devices were introduced. On this basis, the processes of the model tests were then delineated. The fire loading conditions were determined by analyzing the lining structure. The two tests were then conducted, and the detailed results were presented. Changes to the test processes and the distribution of temperatures on the inner wall surfaces as well as the deformation and failure modes of the segments were closely analyzed. The results of the study showed that the temperature loading equipment and external pressure loading device for the lining can meet the requirements of the model test for thermomechanical coupling research of the whole lining. At the beginning of the test, the heating rate at the bottom lagged behind that of the top; however, results show that the differences between the parts decrease gradually with continuous heating, and a stable temperature field can form inside the lining. The failure mode of the homogeneous segment without an external force is characterized by penetration cracks along the width of the segment, and differences exist in the development paths of the segments. The compressive strain produced by the external pressure decreases with increasing temperature, and external pressure load has an inhibitory effect on the expansion deformation of the lining structure at high temperatures. The results can be used as a reference for further development of thermomechanical coupling research of whole ring lining in shield tunnels.