Abstract: Piping is a most common failure mode in binary structure dikes. Accurate detection of dike piping channels during high water levels is of great significance to the study of piping evolution and risk prevention and reinforcement project. This paper presents a technique for detecting weak magnetic field signals in embankment seepage channels. In the light of the conductivity of seepage water, an artificial electric current is supplied to the outlet of piping channel. By detecting the weak magnetic field signal generated by the conduction loop in the dike surface, the distribution of piping channel can be rapidly identified. The distribution characteristics of weak magnetic field in piping channel are analyzed by numerical calculations. To address the challenge of weak magnetic field signal detection, a method of extracting weak magnetic signal based on phase-locked amplification method and conductor source interference of the same frequency is proposed to reduce the influence of dike undulating terrain and enhance the energy of weak magnetic signal. Field tests of piping detection were carried out on a dike in Poyang Lake basin to find out the distribution of potential piping paths effectively. This study will contribute to improving the accuracy of detecting piping channel in dike, enabling early detection and mitigation of piping hazards, and providing technical support for emergency response of piping incidents.

Key words: hidden danger of dike, piping channel, Magnetometric Resistivity (MMR) method, weak magnetic characteristics, weak magnetic signal detection technology