Abstract:

Lining instability is common in excavation sections of large water diversion channels with high groundwater levels during the operation period. Effective seepage control measures are crucial for ensuring channel lining safety. This study addresses the lining instability issue in a canal section of the middle route of the South-to-North Water Diversion Project following the ‘7·20’ heavy rainstorm in Henan in 2021. Based on monitoring data and three-dimensional seepage simulation, the causes of the canal lining plate instability were analyzed, and the effects of additional vertical relief wells and transverse drainage pipes on the canal slope were evaluated using a three-dimensional model. Results show that the permeable strata in the channel foundation provide a seepage pathway for rainfall infiltration and lateral groundwater recharge. The rise in groundwater level due to extreme rainfall is the primary cause of canal lining plate instability. Drainage measures could effectively reduce the uplift pressure beneath the lining plate. These findings offer insights for the risk analysis, regulation, and operational management of similar canal sections.

Key words: water diversion channels, high groundwater level, uplift pressure, lining instability, seepage analysis