Bauxite mining beneath coal mining goaf faces significant threats from water-related hazards, including water accumulation in the overlying coal goaf and the underlying Ordovician limestone aquifer. In this study, Brazilian tests were performed on bauxite specimens with varying water saturations (0, 25%, 50%, 75%, and 100%) using digital image correlation (DIC) and three-dimensional surface scanning to examine their damage evolution and splitting characteristics. Furthermore, molecular dynamics simulations, environmental scanning electron microscopy (ESEM), and computed tomography (CT) were employed to investigate the underlying mechanisms. The results indicate that diaspore, the primary component of the studied bauxite, exhibits strong hydrophilicity. Molecular dynamics simulations further reveal that water molecules readily form hydrogen bonds with the hydroxyl groups on the diaspore crystal surface. As water saturation increases, both the tensile strength and fracture energy of bauxite gradually decrease, reflecting its resistance to splitting failure weakens. The JRC and fractal dimension of the splitting surfaces progressively rise, reflecting greater morphological complexity. ESEM analyses confirm the fracture mode of diaspore-type bauxite shifts from transgranular fracture to intergranular fracture. CT test results exclude mineral dissolution as a factor affecting strength. Friction test results show that the intergranular friction resistance of diaspore crystals decreases with increasing water saturation, which directly contributes to the reduction in the tensile strength of bauxite. These findings provide critical experimental insights for ensuring the safety and efficiency of bauxite mining.Highlights<OrderedList> <ListItem> <ItemNumber>(1) </ItemNumber> <ItemContent> The tensile strength and damage evolution characteristics of Shanxi coal-measure bauxite under water–rock interaction were revealed, providing an experimental basis for evaluating pillar stability. </ItemContent> </ListItem> <ListItem> <ItemNumber>(2)</ItemNumber> <ItemContent> A parametric program was developed to quantitatively characterize the morphology of bauxite splitting surfaces through Joint Roughness Coefficient (JRC) and fractal dimension calculations. </ItemContent> </ListItem> <ListItem> <ItemNumber>(3)</ItemNumber> <ItemContent> The strength degradation and fracture mechanisms of diaspore-type bauxite with varying water saturations were elucidated from the atomic-scale bonding behavior, crystal fracture modes, and frictional resistance. </ItemContent> </ListItem> </OrderedList>

Experimental Investigation into the Influence of Water Saturation on the Tensile Failure Behavior of Diaspore-Type Bauxite: Implications for Underground Mining of Bauxite

期刊论文
发表日期：

2025年12月8日

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Defu Zhu,
Wenshuo Hu,
Yalin Li,
Qingsheng Bai,
Yongjie Jia,
TengFei Fu,
Gan Feng,
Yujiang Zhang,
Xiaosong Sun,
Yongqing Lin,
Dingwei Sun

摘要

Bauxite mining beneath coal mining goaf faces significant threats from water-related hazards, including water accumulation in the overlying coal goaf and the underlying Ordovician limestone aquifer. In this study, Brazilian tests were performed on bauxite specimens with varying water saturations (0, 25%, 50%, 75%, and 100%) using digital image correlation (DIC) and three-dimensional surface scanning to examine their damage evolution and splitting characteristics. Furthermore, molecular dynamics simulations, environmental scanning electron microscopy (ESEM), and computed tomography (CT) were employed to investigate the underlying mechanisms. The results indicate that diaspore, the primary component of the studied bauxite, exhibits strong hydrophilicity. Molecular dynamics simulations further reveal that water molecules readily form hydrogen bonds with the hydroxyl groups on the diaspore crystal surface. As water saturation increases, both the tensile strength and fracture energy of bauxite gradually decrease, reflecting its resistance to splitting failure weakens. The JRC and fractal dimension of the splitting surfaces progressively rise, reflecting greater morphological complexity. ESEM analyses confirm the fracture mode of diaspore-type bauxite shifts from transgranular fracture to intergranular fracture. CT test results exclude mineral dissolution as a factor affecting strength. Friction test results show that the intergranular friction resistance of diaspore crystals decreases with increasing water saturation, which directly contributes to the reduction in the tensile strength of bauxite. These findings provide critical experimental insights for ensuring the safety and efficiency of bauxite mining.

Highlights (1)

The tensile strength and damage evolution characteristics of Shanxi coal-measure bauxite under water–rock interaction were revealed, providing an experimental basis for evaluating pillar stability.

(2)

A parametric program was developed to quantitatively characterize the morphology of bauxite splitting surfaces through Joint Roughness Coefficient (JRC) and fractal dimension calculations.

(3)

The strength degradation and fracture mechanisms of diaspore-type bauxite with varying water saturations were elucidated from the atomic-scale bonding behavior, crystal fracture modes, and frictional resistance.