Geological Safety of Water Inrush in Complex Seabed Mining: A Case Study of X Gold Mine

A portion of the X gold mine extends into the seabed, where the engineering geological conditions are characterized by complexity, predisposing the area to water inrush hazards. To mitigate the adverse effects of such hazards within the mining vicinity, a comprehensive approach involving the scanline method, transient electromagnetic method (TEM), and numerical simulation technique was employed. These methods were applied to assess and simulate conditions along the - 165-m horizontal tunnel in the mining area. The findings indicate that the primary geological structure of the rock strata within the L1# and L2# tunnels is predominantly layered, with partially developed joints, thereby augmenting the potential for slip and flexural overturning. Conversely, the risk of direct overturning is deemed negligible. TEM surveys revealed that the Quaternary (Q) layer has a thickness ranging from 0 to - 5 m, while the regolith extends from - 5 to - 40 m. The predominant rock types in this region are metamorphic feldspar and medium- to fine-grained monzonitic granite. The water-bearing zone spans from approximately - 40 to - 160 m, while the underlying anhydrous rock formation extends from - 160 to - 165 m. The theoretical calculation determines the relationship between the critical threshold of acceptable water pressure in the aquifer and the shortest propagation path of water inrush originating from the fault source. By monitoring the stress, displacement, and seepage behaviors within the roof, floor, and fault region of the tunnel, it is observed that the activation of the fault occurs once the excavation reaches a distance of 40 m from the fault. This activation establishes a hydraulic linkage with the aquifer, significantly amplifying the mining risk within the fault zone of the mining area. Henceforth, to uphold safety standards, vigilant monitoring of stress, displacement, and variations in water pressure at a distance of 40 m from the fault is imperative. Corresponding preventive measures must be promptly implemented to forestall the onset of water inrush incidents.