Abstract: The exploitation of resources in coastal area is one of the trends of contemporary mining development. Cemented backfill bottom （CBB） stability is the key factor of underground safety mining. However， the CBB can be corroded and lose strength easily under the brine environment in coastal mines， posing huge threatens to the coastal resource exploitation. Based on the engineering background of a large-scale coastal gold mine in China， this study collects samples on site， simulates the internal corrosion environment of the filling false bottom by using self-made laboratory equipment， and uses electrochemical analysis and other interdisciplinary methods are used to study the corrosion behavior of HPB235 steel in the CBB. The strength test and XRD analysis of cement paste test block show that salt halide ion is conducive to the formation of hydration reaction products， and is beneficial to the early strength of cemented test block. The main reason for the instability of CBB is the corrosion of HPB235 reinforcement structure.And the steel electrochemical corrosion behaviors under different protective measures are studied by open circuit current measurement， potentiodynamic polarization test， electrochemical impedance spectroscopy （EIS） and weight-loss method respectively. The result shows that significant corrosions have been found in the unprotected steel bars. The corrosion rate is up to 4.828 g/m2/d. And the epoxy resin coating is proven to be an effective measure which can reduce the current density by 95.8% and the corrosion rate by 93.8%. However， the corrosion inhibitor can only be an auxiliary measure based on its limited effect.

Key words: backfill mining, coastal mine, cemented backfill bottom, steel corrosion, electrochemical test