Unlike land mining, the safety of seabed mining is seriously threatened by an overlying water body. In order to ensure the safety of subsea mining projects, it is of great importance to understand the failure characteristics and influencing factors of overlying strata deformation. Focusing on the Sanshandao Gold Mine, a typical submarine deposit in China, geomechanical model testing and numerical simulations were carried out. The results show that in the mining of a steeply dipping metal ore body, subsidence deformation mainly occurs on the hanging wall; the subsidence center is located on the surface of the hanging wall, and the uplift center is located on the upper surface of the ore body. The critical mining upper limit, which represents the minimum thickness of the reserved isolation pillar between the overlying seawater and the goaf, was determined to be 50 m in the Xinli mine; fault slip would occur if this critical value was exceeded. The dip angle and thickness of the ore body were negatively correlated with the vertical surface deformation. As the dip angle and thickness increased, the critical upper mining limit increased. When the fault was located in the footwall, the critical upper mining limit increased as the distance between the fault and the ore body increased, and the failure mode of the goaf was fault slip. When the fault was located in the hanging wall, the final failure mode of the goaf changed to a combined failure mode of overlying rock collapse as well as fault slip. These research results provide a theoretical basis for the selection of the reserved pillar height in the Xinli mining area, as well as a reference for safe mining practices under similar geological conditions.

中文翻译：

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海底开采上覆地层变形破坏特征及临界开采上限案例研究

与陆地采矿不同，海底采矿的安全受到上覆水体的严重威胁。为保障海底采矿工程的安全，了解覆岩变形破坏特征及影响因素具有重要意义。以我国典型海底矿床三山岛金矿为研究对象，开展地质力学模型试验和数值模拟。结果表明，在陡倾金属矿体开采中，沉降变形主要发生在上盘；沉降中心位于上盘表面，隆起中心位于矿体上表面。临界开采上限，表示上覆海水与采空区之间预留隔离柱的最小厚度，确定为新丽矿50m；如果超过这个临界值，就会发生故障滑移。矿体倾角和厚度与地表垂向变形呈负相关。随着倾角和厚度的增加，临界开采上限增加。当断层位于下盘时，临界开采上限随着断层与矿体距离的增加而增加，采空区的破坏模式为断层滑动。当断层位于上盘时，采空区的最终破坏模式转变为上覆岩体崩塌和断层滑动的组合破坏模式。这些研究成果为新丽矿区预留柱高的选择提供了理论依据，