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| Visualizing seepage-erosion and pattern transitions in rough rock fractures |
| LIU Xianshan1, 2*, LIU Yang1, YANG Zhibing3, HU Ran3, CAO Yiting1, YANG Wenyuan1, SONG Yulin1, HUANG Zixuan1 |
| (1. School of Civil Engineering, Chongqing University, Chongqing 400045, China; 2. State Key Laboratory of Safety and Resilience of Civil Engineering in Mountain Area, Chongqing University, Chongqing 400045, China; 3. State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan, Hubei 430072, China) |
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Abstract The dissolution process in rock fractures is jointly controlled by advection, reaction, and diffusion, leading to the formation of compact dissolution, wormhole dissolution, and uniform dissolution patterns. Wormhole dissolution can create localized preferential flow channels, significantly altering the permeability of rock masses and accelerating reservoir leakage or dam foundation instability. Therefore, understanding these pattern transitions is crucial. Using rough rock fractures as a case study, a visual experimental platform for fracture dissolution was developed to conduct flow-dissolution tests under varying flow velocities and reaction rates. This platform successfully reproduced the co-evolution of dissolution morphology, aperture changes, and pattern transitions in rough fractures, aiming to investigate the underlying mechanisms. The results indicate that as flow velocity increases, the dissolution pattern transitions first from compact to wormhole dissolution, and then from wormhole to uniform dissolution. An increase in the reaction rate raises the critical Péclet number (Pe) required for the transitions from compact to wormhole dissolution and from wormhole to uniform dissolution. Considering that the solute concentration field is primarily influenced by the relationship between longitudinal (horizontal) and transverse mass transfer, a condition number for dissolution pattern transition was defined as the ratio of the longitudinal to transverse mass transfer coefficients. The critical values of this condition number were identified as 350 for the transition from compact to wormhole dissolution and 7 for the transition from wormhole to uniform dissolution. The findings of this research elucidate the dissolution processes and pattern transitions in fractures within soluble rock areas, providing a scientific basis for evaluating seepage stability and optimizing seepage control measures for reservoir banks and dam foundations in hydropower engineering projects.
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2026, Vol. 45 
