Smart Monitoring of Cyclic Freeze–Thaw Damage of Lining Concrete Using Dual‐Channel Feature Fusion of Piezoelectric Conductance and Stress Wave Signals

The durability and stability of cold regional tunnels are extensively threatened by cyclic freeze–thaw environments, highlighting the necessity of accurate monitoring and assessing the accumulative damage within lining concrete. This study proposed an innovative integrated sensing strategy that concurrently incorporated the piezoelectric‐based electromechanical impedance (EMI) and wave propagation (WP) techniques for the detection of cyclic freeze–thaw damage in bended concrete. First of all, the visual inspection and four‐point flexural testing were performed to study the characteristics of damage evolution and strength deterioration of cyclically freeze–thawed concrete under different bending loads. In addition, the coupling effect of freeze–thaw cycling and bending on damage progression was interpreted. The degrading flexural strength was employed to quantify the overall damage degree. Moreover, the performances of EMI and WP methods in monitoring the concrete freeze–thaw damage were explored by analyzing the varying conductance and stress wave signatures based on conventional approaches. It was found that the statistic metrics of conductance and energy of stress wave signals served as reliable indicators of damage. The key novelty of this study was that a dual‐channel feature fusion network (DCFF‐Net) was developed to extract and coordinate damage‐relevant features from cross‐dimensional conductance and continuous wavelet transform spectral data, enabling automated and intelligent damage assessment. The proposed framework demonstrated a substantial improvement in damage classification performance, achieving accuracies exceeding 0.98 on two distinct datasets. This performance notably surpassed that of single‐sensing methods. These findings manifested the feasibility and effectiveness of leveraging dual‐channel piezoelectric data fusion for improved detection and characterization of complex damage evolution within concrete infrastructures.