Abstract: The compaction and penetration tests of highly plastic clay, located between the dam core wall and cushion concrete in Nuozhadu hydropower station, are performed. The compaction mechanism and the influence of different construction technological parameters such as grain composition, filling thickness and compaction times, etc. are discussed by the field roller compaction and penetration test. On the basis of the test, the optimal technological parameters and quality control specification of the given project are found by contrast tests for which various detection methods such as compaction settlement, watering method and cutting ring are adopted. And field compaction and penetration quality control method of highly plastic clay is put forward; namely, differential settlement and compaction is given priority but construction technological parameters must be considered at the same time. The method may insure filling quality effectively and quicken construction progress. And it also can provide scientific data, standards for the quality control, quality check, quality evaluation of the projects for which highly plastic clay soil is adopted as filling material. It has significant applicable value.

Key words: soil mechanics, highly plastic clay, compaction property, penetration property