Unidirectional Energy Dissipation‐Based Piezoelectric Ultrasonic Monitoring of Anchor Bolt Axial Force

Monitoring the axial force of anchor bolts is critical for ensuring the safety of geotechnical engineering structures. This paper proposes a novel method based on piezoelectric active sensing to accurately assess anchor bolt axial force. The method exploits variations in signal energy dissipation at the contact interface within the anchoring system under load, addressing the limitations of traditional piezoelectric techniques in monitoring stability and zero‐point quantification. The contact interface characteristics of the anchor bolt system were analyzed, and a unidirectional energy dissipation path was designed to ensure stable signal acquisition. Key indicators were extracted using the Welch power spectral density estimation method, and a mathematical model relating axial force to these indicators was established. The model’s reliability was validated through multiple independent experiments along three test paths. Results demonstrate a strong linear correlation under various conditions, with an average monitoring error within 10%, enabling precise identification of absolute axial force. The proposed method features real‐time performance, high accuracy, and robust anti‐interference capability, providing a reliable technical approach for anchor bolt axial force monitoring in geotechnical engineering applications.