Coefficient of earth pressure at rest of a saturated artificially mixed soil from oedometer tests

The present study focuses on the coefficient of earth pressure at rest (K₀) of a saturated crushed binary soil mixture. The mixture is artificially mixed by crushed sandstone and mudstone particles according to presupposed weight ratios and particle size distribution curves. The oedometer tests are performed to determine the coefficient K₀. From test data, the values of coefficient K₀, which range from 0.242 to 0.381, with a mean value of 0.300, are obtained. Just as other mechanical parameters of soils, the K₀ value is affected by many factors. The effects of the properties of test specimen and material are discussed on the basis of the test data. Strong negative correlation between the values of K₀ and initial dry bulk density of test specimen, one between the values of K₀ and median particle size diameter of test material, and one between the values of K₀ and gravel content by weight of test material, respectively, are observed from the test data. The mudstone particle content by weight of the mixture may also affect the value of K₀. The effects of these factors on the K₀ value may exhibit interlocking effect. Higher interlocking effect results in higher shear strength, and therefore results in lower K₀ value.