Abstract:The seepage of dam foundation of Wanghuating reservoir is analyzed according to the hydrogeological and engineering conditions. It is pointed out that the total width of the marble outcrop under the dam block between stake 0+165-0+430 is 265 m. The fifth and seventh layers of the marbles are 38% of the total width of dam site,but its seepage amount accounts for 69.7% of the total seepage amount. Thus there are hidden troubles of sinkholes,swamps of big area,piping of the highly permeable layer and contact erosion. Therefore,the treatments of curtain grouting and hole-top enclosure curtain grouting to the dam foundation are considered. According to the requirement for the preliminary design phase,the method of sectioned grouting from top to bottom with hole-top enclosure is adopted. But the grouting test results show that the method is difficult to carry out and the grouting effect is unsatisfying. Problems such as trouble watertight plug,serious grout-recycling in the hole,considerable emission of slurry to the dam body and out the top of dam occur. By many tests,the sectioned grouting from top to bottom in bedrock with slurry cycling within hole and enclosure at dam body and hole top is employed. The results of testing and practical grouting show that the grouting effects is excellent in spite of some difficulties in execution. The development of this new method,testing,construction techniques and quality inspection are introduced.