Fig. 1. Acoustic signal of broken wire

Fig. 2. Structural diagram of broken wire detection system of PCCP pipeline merged with Φ‑OTDR and MZI

Fig. 3. Schematic of IQ demodulation

Fig. 4. Schematic of the position of PZT

Fig. 5. Original waveform diagrams

Fig. 6. Φ-OTDR system with applying 10.1 kHz vibration signal by PZT

Fig. 7. MZI system with applying 10 kHz vibration signal by PZT

Fig. 8. Time domain spectrum of different vibration signals

Fig. 9. Frequency spectrum of different vibration signals

Fig. 10. Broken wire simulation device

Fig. 11. Layout of the optical fiber on the plate

Fig. 12. Time domain waterfall plot during the drop of the steel sphere

Fig. 13. Location information of the sphere drop

Fig. 14. Position of five-time sphere drops