Li Chuan, Li Jiaqi, Luo Chuan, Xu Qiang, Wan Xiaorong, Yang Lubing
Faculty of Information Engineering and Automation, Kunming University of Science and Technology, Kunming 650500, China.
Yunnan Key Laboratory of Computer Technology Applications, Kunming 650500, China.
Sensors (Basel). 2024 Mar 8;24(6):1749. doi: 10.3390/s24061749.
Tunnel excavation induces the stress redistribution of surrounding rock. In this excavation process, the elastic strain in the rock is quickly released. When the maximum stress on the tunnel lining exceeds the concrete's load-bearing capacity, it causes cracking of the lining. Comprehensive geophysical exploration methods, including seismic computerized tomography, the high-density electrical method, and the ultrasonic single-plane test, indicated the presence of incomplete distribution of broken rock along the tunnel axis. Based on the geophysical exploration results, a carbon-fiber-strengthened tunnel simulation model was established to analyze the mechanical characteristics of the structure and provide a theoretical basis for sensor deployment. Fiber Bragg grating (FBG) strain sensors were used to measure the stress and strain changes in the second lining concrete after carbon reinforcement. Meanwhile, one temperature sensor was installed in each section to enable temperature compensation. The monitoring results demonstrated that the stress-strain of the second lining fluctuated within a small range, and the lining did not show any crack expansion behavior, which indicated that carbon-fiber-reinforced polymer (CFRP) played an effective role in controlling the structural deformation. Therefore, the combined detection of physical exploration and FBG sensors for the structure provided an effective monitoring method for evaluating tunnel stability.
隧道开挖会引起围岩应力重新分布。在这个开挖过程中，岩石中的弹性应变会迅速释放。当隧道衬砌上的最大应力超过混凝土的承载能力时，就会导致衬砌开裂。综合地球物理勘探方法，包括地震计算机断层扫描、高密度电法和超声单平面测试，表明沿隧道轴线存在破碎岩石分布不完整的情况。基于地球物理勘探结果，建立了碳纤维增强隧道模拟模型，以分析结构的力学特性，并为传感器部署提供理论依据。采用光纤布拉格光栅（FBG）应变传感器测量碳纤维加固后二次衬砌混凝土的应力和应变变化。同时，在每个断面安装一个温度传感器以实现温度补偿。监测结果表明，二次衬砌的应力应变在小范围内波动，衬砌未出现任何裂缝扩展行为，这表明碳纤维增强聚合物（CFRP）在控制结构变形方面发挥了有效作用。因此，对结构进行物探和FBG传感器的联合检测，为评估隧道稳定性提供了一种有效的监测方法。
