Safe mining technology of undersea metal mine

Xinli district of Sanshandao Gold Mine is the first subsea metal mine in China. To achieve 6 kt/d production capacity under the premise of safe mining, high-intensity mining might destroy the in-situ stress filed and the stability of rockmass. According to sampling and testing of ore-rock and backfill and in-situ stress field measurement, safety factor method calculation model based on stress—strain strength reduction at arbitrary points and Mohr-Coulomb yield criterion was established and limit displacement subsidence values under the safety factor of different limit stoping steps were calculated. The results from three years in-situ mining and strata movement monitoring using multi-point displacements meter showed that the lower settlement frame stope hierarchical level filling mining method, mining sequence are reasonable and rockmass stability evaluation using safety factor method, in-situ real-time monitoring can provide the technical foundation for the safety of seabed mining.