Research and application on large-scale coarse-grained soil filling characteristics and gradation optimization

Abstract

The filling characteristics of rockfill is an engineering problem that cannot be ignored in high dams. Reasonably controlling and optimizing the gradation is critical for improving the compaction quality. The relationship between gradation distribution law and compaction characteristics is investigated using numerical and field experiments, and a method for dam construction gradation design optimization is given. The results show that the Weibull model exhibited better applicability for continuous coarse-grained soil gradation. The extreme porosity of rockfill has a scaling effect, which can be basically eliminated when the maximum particle size reaches 400 mm. The prediction results based on the neural network show that the Weibull model gradation parameters strongly correlate with the porosity. The “occupancy effect”, or “filling effect”, of fine particles, and the “wedge effect”, or “wall effect”, of coarse particles, can explain the relationship between the Weibull model gradation parameters and porosity. The gradation parameters have a corresponding relationship with the classical non-uniformity coefficient Cu and curvature coefficient Cc indexes. Cu and Cc indicators can be used to judge the quality of the gradation at first and then optimize it by using the experimental results of the Weibull model parameters. The research results have application reference value for the filling design and compaction quality evaluation of large-scale coarse-grained soil.

Graphical abstract