Impact of the Plate Diameter on the Value of the Pre-Compaction Stress in Soils With Varied Textural Group

The objective of the paper was to verify the previously obtained results of research concerning the impact of the plate diameter on the measured value of the pre-compaction stress of silt (NG), in conditions of a wider range of soil types and their initial stage. The research was carried out on samples with a diameter of 100 mm and height of 30 mm produced from the soil material (M) or collected from the subsoil of the selected soils (AWN) with the granulation type of: silt loam, loam, light loam, sandy-clay soil. The following soils properties were determined: the granulation type, density of the solid phase, content of humus and calcium carbonate, reaction, plastic and liquid limit. The properties of samples were described with moisture, dry density of solid particles, porosity of aeration, degree of plasticity and degree of saturation. The samples were loaded with a testing machine with plates with varied diameters. The value of the pre-compaction stress of soil was measured with the method of searching the crossing point of tangents with the secondary stress curve and the original stresses curve (a classical method). It was found out that for samples M with the degree of saturation of 0.40-0.50, the pre-compaction stress does not significantly depend on the plate diameter. For samples M or AWN, with the degree of saturation of 0.64-0.82, the pre-compaction stress significantly depends on the diameter of the plate. A conclusion was formulated that in the research of NG with the method of uniaxial defonnations, the relation of the diameter of the plate (d) to the diameter of the cylinder (D) should be within 0.5 ≤ d/D ≤ 0.8.