Structural Health Monitoring of Underground Structures in Reclamation Area Using Fiber Bragg Grating Sensors  
[PERSON]  
1 School of Civil Engineering, Sun Yat-sen University, No. 135 XinGangXi Road, Guangzhou 510275, China; [EMAIL_ADDRESS] (Z.L. ); [EMAIL_ADDRESS] (P.L. ); [EMAIL_ADDRESS] (Y.H.) 2  
[PERSON]  
1 School of Civil Engineering, Sun Yat-sen University, No. 135 XinGangXi Road, Guangzhou 510275, China; [EMAIL_ADDRESS] (Z.L. ); [EMAIL_ADDRESS] (P.L. ); [EMAIL_ADDRESS] (Y.H.) 3  
[PERSON]  
1 School of Civil Engineering, Sun Yat-sen University, No. 135 XinGangXi Road, Guangzhou 510275, China; [EMAIL_ADDRESS] (Z.L. ); [EMAIL_ADDRESS] (P.L. ); [EMAIL_ADDRESS] (Y.H.) 2 Guangdong Engineering Research Centre for Major Infrastructure Safety, Guangzhou 510275, China  
3  
[PERSON]  
1 School of Civil Engineering, Sun Yat-sen University, No. 135 XinGangXi Road, Guangzhou 510275, China; [EMAIL_ADDRESS] (Z.L. ); [EMAIL_ADDRESS] (P.L. ); [EMAIL_ADDRESS] (Y.H.) 2 Guangdong Engineering Research Centre for Major Infrastructure Safety, Guangzhou 510275, China  
3  
[PERSON]  
4 Department of Infrastructure Engineering, The University of Melbourne, Melbourne, VIC 3010, Australia; [EMAIL_ADDRESS]  
4 Correspondence: [EMAIL_ADDRESS]; Tel. : +86-020-8411-1124  
a real-time warning system for crack formation in underground structures. To further understand the deformation mechanism of underground tunnels, [PERSON] et al. (2018) obtained detailed deformation information on the surface of a tunnel using a ground laser scanner. In addition, previous experimental studies revealed that FBG sensors have stronger anti-interference abilities and higher monitoring accuracies than traditional sensors ([PERSON] _et al._, 2017; [PERSON] _et al._, 2018; [PERSON] _et al._, 2018). Data processing plays an important role in the structural health of underground road structures. The Braided Cooperative Reliable Transport (BCRT) is a data processing algorithm which is widely used to analyze the collected data with high efficiency ([PERSON] _et al._, 2018). To overcome the difficulties in analyzing the large amount of collected data, [PERSON] et al. (2018) proposed an improved parallel clustering algorithm based on K-means. In addition, to quantify the nonlinear relationship between intrinsic soil parameters and tunnel convergence, the monitoring data can be analyzed using a methodology based on the support vector machine (SVM) and a Back-Propagation (BP) neural network algorithm ([PERSON] _et al._, 2018; [PERSON] _et al._, 2018). Further, a K-means clustering method has been developed to determine the optimal number of clusters by investigating the relationship between mixed ratio, tunneling parameters and silhouette evaluation ([PERSON] _et al._, 2018). To identify the critical factors that affect the structural condition of underground structures, [PERSON] et al. (2018) analyzed the influence of landslides on crack development in tunnels, while [PERSON] et al. (2018) studied the effects of continuous rainfall on the surrounding rock deformation in shallow-buried highway tunnels. In addition, to investigate the influence of seismic loading on the tunnels, a numerical model was proposed to predict the thrust generated during the slip process of the tunnel lining by measuring the slip between the tunnel lining and the ground soil ([PERSON] _et al._, 2018). However, to date, traditional monitoring techniques, such as resistance, inductive and potentiometric sensors, have poor anti-jamming ability and lower sampling frequency for long-term monitoring of underground structures in a complex environment. With a sampling frequency of 1000 Hz, fiber Bragg grating sensing monitoring technology has the capability to monitor multiple critical factors that affect the structural conditions of underground structures simultaneously through continuous long-term data collection.