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Ultra-long and large-diameter underwater bored piles are widely used in deep-water bridge foundations; however, key construction parameters such as concrete surface elevation and tremie conduit embedment depth are still largely measured manually, resulting in low levels of automation and limited data traceability. Accurate monitoring of these parameters is essential to ensure construction quality and prevent defects such as pile breakage or mud inclusion. This study aims to develop an intelligent monitoring system to achieve real-time and automated measurement of concrete pouring height and conduit embedment depth during underwater pile construction. An integrated intelligent sensing system was developed combining fiber Bragg grating (FBG) pressure sensors, distributed fiber optic temperature sensing (DTS), RFID-based conduit counting, and a PLC-controlled automated monitoring device. Laboratory experiments and field tests were conducted to evaluate the feasibility of fiber optic pressure and temperature sensing for detecting the concrete interface. Laboratory tests demonstrated that fiber optic pressure and temperature sensors can effectively identify the interface between mud, laitance, and concrete during pouring. Field experiments showed that concrete level monitoring based on intelligent sensing achieved an error ranging from 0.25 m to 0.5 m, while dynamic tracking of the concrete surface achieved accuracy within approximately 0.3 m. The system was successfully applied in the Hangzhou Bay Cross-Sea Bridge project, confirming its reliability in engineering practice. The proposed monitoring system significantly improves the automation and informatization of underwater bored pile construction. Compared with traditional manual sounding methods, it provides higher monitoring frequency, improved accuracy, and real-time data transmission through a cloud platform, enabling traceable management of concealed works. The system offers a practical and cost-effective solution for intelligent construction of deep foundations and supports the digital transformation of pile foundation engineering.