Research On Particle Size Distribution And Compaction Characteristics Of Silts

Silt is one kind of soils those have bad engineering performance. There are many technical difficulties when the subgrade is being compacted, which brings great harassment to highway construction. Silts are difficult to become compaction. It is generally believed that the reason for this phenomenon is the lack of fine particles. However, there have not given a clear explanation by existing studies. Therefore, it is very necessary to comprehensively analyze the characteristics of particle size distribution and identify the essential reason which affects silt compaction.In this paper, five silts in different tenders of an Expressway were selected to analyze by laboratory test and pointed out the essential factor which affect silt compaction. On this basis, the relationship between this factor and dry density of compaction silts was studied. Compaction property of silt is studied not only by compaction test, but also by vibrating compaction test with vibrating compaction equipment developed by Chang’an University. Test results showed that specimen molding method and moisture all affect process of silt compaction, but they are not the key factor which affects the density of compaction silt. Particle size compositions of different silts were measured with Mastersizer 2000 Laser Particle Size Analyzer. Based on the fractal theory, the character of silt Particle size distribution was analyzed and point that the statistical self-similarity of grain—size distribution existed in the silts. Fractal dimension can be more fully reflected the cumulative size distribution curve characteristics. Taking the fractal dimension as the particle size distribution characterization parameters, maximum dry density as compaction parameters, the relativity between them was studied. As a result, the deviation coefficient was put forward, Which reflect the fractal dimension deviation between silt particle size distribution and the most packed theoretical curve—Fuller curve. And the relationship equation of maximum dry density and deviation coefficient was established.