SOILCOMPACTION: THE EFFECT OF GRAIN SIZE DISTRIBUTION

GOH HOCK SWEE

SUMMARY

Soil samples and soil clods were collected from eleven sites in Eastern Oregon. Their grain size distributions were determined.The soil samples were equilibrated to three matric suctions, and compacted by a series of staticpressure. Semilog graphs of bulk density versus pressure obtained were linear over the range of applied stress and moisture content of the experiment. The slopes of the graphs with different moisture content the same soils were parallel to each other. This indicates that the slopes of the graphs and the compression index are independent of the moisture content. The minimum static stresses required to produce the clod bulk densities found in the field were estimated in the laboratory. The limitations of this calculation are discussed. A multiple regression ofthe dependent variable, bulk densities on the independent variables of grain size and organic matter was carried out. Fine silt content together with total sand accounted for 90% of the variation in bulk density.

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