Abstract: Seepage field regulation is crucial for the stability of canal slope and liner plate along the middle route of the South-to-North Water Transfer Project, especially for stretches excavated in expensive soil area with high groundwater level. In this article, the seepage field of a typical section was simulated with 3-D finite element technology to investigate into the rationality and effectiveness of seepage regulation measures comprehensively. The distribution of seepage field was analyzed and the seepage control measures were compared. Results show that the uplift pressure on canal pavement would be reduced significantly by drainage cushion with drainage holes opening only when groundwater level is higher than the canal water level, by drainage cushion replaced by drainage board, and by drainage holes replaced with permeable joints of liner plate in addition. The differences in the three measures were compared, and their application conditions were discussed and corresponding suggestions were given.

Key words: middle route project of South-to-North Water Transfer, excavation canals, drainage cushion, water pressure head, seepage field regulations, numerical simulation