基于FBG智能锚杆的大断面输水隧洞结构健康监测研究

Structural Health Monitoring of Large-Cross-Section Water Conveyance Tunnel Based on Fiber Bragg Grating Intelligent Bolt

光纤光栅技术(FBG)由于其体积小、结构简单和抗干扰能力强等优点在隧道等恶劣环境中被广泛应用,将光纤布拉格光栅技术与支护锚杆相结合,提出基于FBG的智能锚杆监测手段,介绍智能锚杆的测试原理、制作过程,通过室内试验对智能锚杆测点波长变化量与锚杆受力大小的关系进行标定,结果表明其具有较高的线性拟合度。进一步将FBG智能锚杆应用于平阳大断面输水隧洞围岩变形监测中,并结合FBG应变计获取的钢拱架应变数据对锚杆支护效果进行评价。监测结果表明智能锚杆能够实现较为准确的围岩应力测量,在钻爆隧洞施工阶段,锚杆从表面沿深度方向所受压力逐渐减小,由于锚杆的支护作用,降低了钢拱架的受力强度。

The fiber Bragg grating(FBG)technology is widely used in tunnels with harsh environments because of its small size,simple structure,and strong anti-interference ability.In this study,the FBG technology is combined with the supporting bolt to propose an intelligent bolt monitoring method based on FBG,the testing principle and manufacturing process of the intelligent bolt are presented,and the relationship between the wavelength change of the measuring point of the intelligent bolt and the stress of the bolt is calibrated through indoor tests.The test results indicate a high linear fit.Furthermore,the FBG intelligent bolt is applied to the surrounding rock deformation monitoring of the Pingyang largecross-section water conveyance tunnel,and the bolt support effect is evaluated in combination with the steel arch strain data obtained by FBG strain gauge.The monitoring results show that the intelligent bolt can achieve more accurate measurement of surrounding rock stress.During the construction of the drilling and blasting tunnel,the pressure on the bolt along the depth direction from the surface gradually decreases.Due to the supporting effect of the bolt,the stress strength of the steel arch is reduced.