Abstract:

The dry density of soft rock rockfill is an important control index for the design and construction of earth-rock dams, as it directly influences the settlement of earth-rock dams during construction and operation. The Φ950 mm×H1 000 mm super-large compactor was used to conduct compaction tests under five levels of compaction energy, including 483, 992, 1 475, 1 957,2 681 kJ/m³, for the strongly weathered silty mudstone, weakly weathered silty mudstone,and a mixture of silty mudstone. The results were compared with those from φ300 mm×H285 mm large compaction test. The test results show that the dry density increases with the increase in compaction energy.When the compaction energy is less than 2 000 kJ/m³, the dry density increases rapidly with increasing the compaction energy. When the compaction energy exceeds 2 000 kJ/m³, the rate of increase slows down and the increment is small. Further increasing the compaction energy does not significantly improve the dry density.Under the same compaction energy, the maximum dry density from the ultra-large compaction is slightly lower (by 0.01 to 0.02 g/cm³) than that from the large compaction test. The size effect of soft rock rockfill on compaction characteristics is not significant, and under the heavy standard compaction functional conditions, it is appropriate to use a compaction instrument with a diameter of 300 mm to study the compaction characteristics of soft rock rockfill indoors.

Key words: soft rock rockfill, super-large compaction instrument, dry density, compaction energy, size effect, particle crushing rate