Abstract: Some questions such as disqualification dam, many cracks in developing dam body, disperse-impregnation in the downstream slope of dam, forming ascending spring owing to marshization in dam back, wadding educts coming from drainage ditch and rearing pond and a lot of seepage amount were occurred. These abnormal phenomena were brought by the seepages in the body and foundation of dam. On the circumstances of describing the dam body, foundation geological and hydrogeological conditions, cause of formation of the dam seepage and seepage stability of the dam were analyzed. It is pointed out that the actual saturation line and seepage amount of dam body were abnomal. Especially, the reservoir level was beyond 194 m after 1987, that compared with beforetime, it was abnomal that the identical reservoir level tended to go up. The actual seepage quantity of the dam foundation was unconventional, there were the questions of piping of the highly permeable layer and contact erosion, especially, the reservoir level was under 193.84 m, sand boil in ascending spring behind dam appears. Therefore, the seepage of dam was dangerous. The reasons of formation of dispersed-impregnation and exudates in dam, ascending spring, marshization, the seepage of shoulder and by-pass dam were analyzed.

Key words: dam body, dam foundation, seepage amount, seepage stability, deformation under seepage, Doupo Reservoir