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This paper presents a case study of risk assessment for coal mining under sea area in the Beizao Coalmine, Shandong Province, China. The coalmine is facing the risk of sea water inrush hazards because most of its panels are under the Bohai Sea. To forecast water disaster, three important factors, including efficient aquifuge, water flowing fractured zone and the water pressure bearing capacity of aquifuge, are considered to assess the mining safety situation for Panel H2301 in the Beizao Coalmine. The efficient aquifuge is identified by lithological analysis and water chemical comparison between sea water and groundwater. The water flowing fractured zone under different mining conditions is obtained by statistically analyzing the field measurements and numerical simulation. The safety mining condition under the Bohai Sea is assessed and the upper mining limit of Panel H2303 has been proposed.

This paper presents a statistical prediction of the height of water flowing fractured zone due to coal mining under sea area. Some field measurement methods were used in the Beizao, Liangjia, Wali and Huangxian Coalmines in Shandong Province, China, to investigate the failure process and the maximum height of water flowing fractured zone under different mining and geological conditions. Then, a statistical method has been adopted in this paper for accurately predicting the height of the water flowing fractured zone from the field measurements. The results show that the height of water flowing fractured zone Hf is mainly determined by cutting thickness of seam m in a non-linear relationship, which can be expressed as \( H_{f} = 58.26 \cdot (1 - e^{ - 0.3m} ) \). This result has been successfully used for coal mining decision-making of new panels in the Longkou coalmining area.