Water migration mechanisms and capillary barrier effects in layered tailings with fine-grained interlayers

BIAN Runze; LIU Di; LU Caiwu; JIANG Song; MA Lianjing; HONG Yong

doi:10.13247/j.cnki.jcumt.20250313

Abstract：Fine-grained interlayers are common sedimentary features in tailings dams and exhibit hy-draulic properties that can substantially alter the water migration,thereby influencing long-term sta-bility and service performance.To clarify capillary water migration mechanisms in layered tailings,this study examined the effects of fine-grained interlayer position and thickness on capillary rise be-havior.A self-developed real-time monitoring system was used to conduct controlled laboratory model tests.Three comparative experimental groups were established by varying interlayer eleva-tion and thickness.Temporal changes in capillary rise height and moisture distribution were con-tinuously monitored to analyze staged migration behavior.The results demonstrate that capillary rise in layered tailings progresses through three stages:rapid ascent,gradual rise,and stabiliza-tion.Columns with higher interlayers achieve significantly higher final capillary rise heights than those with middle or lower interlayers.Increasing interlayer thickness delayes capillary water trans-mission and promotes sustained moisture accumulation within the interlayer,where water content remaines higher than in adjacent tailings.Fine-grained interlayers markedly regulates water migra-tion in both the underlying and overlying tailings.Capillary flow accelerates upon reaching the lower interlayer interface due to strong matrix suction,whereas a capillary barrier formes at the up-per interface,producing a discontinuous capillary zone.Continued water accumulation ultimately overcame this barrier,enabling upward penetration into the overlying tailings.These findings clarify the coupled mechanisms of capillary water migration and capillary barrier formation in lay-ered tailings.They provide a scientific basis for evaluating moisture redistribution and long-term stability risks in fine-grained tailings dams.