Impact of Plate Diameter and Sample Height on the Determined Pre-Compaction Value

Abstract

The objective of the paper was to verify previously obtained results of research on the impact of the plate diameter on the determined value of pre-compaction stress of soil (NG) with a wider selection of dimensions of samples. Tests were carried out on samples with a diameter (D) of 100 mm and heights (H) of 30, 50 or 100 mm produced from the soil material (M) or collected (NNS) from subsoil with the granulation group of: silt loam, loam, sandy loam, sandy clay loam. The following soil properties were determined: granulation type, density of the solid phase, content of humus and calcium carbonate, reaction, plastic and liquid limit. Properties of samples were described with moisture, dry density of solid particles, porosity of aeration, degree of plasticity and saturation. Samples were loaded with plates of varied diameters. The NG value was calculated with the method of searching for the crossing point of tangents with the secondary stress curve and the virgin stresses curve (a traditional method). It was stated that the plate diameter (

Impact of Friction on the Uniaxial Soil Sample Compression Process

“…Based on the analysis of results presented in table 5, one may conclude that a correction of the previously obtained results, where it was stated that the plate diameter (d A ) and the sample heigth (H) do not affect the measurement result with the use of cylinders with the height of H30, when the relation of the plate diameter (d A ) to the cylinder diameter (D) should be within 0.5 ≤ d A /D ≤ 0.8 (Błażejczak and Dawidowski, 2016b), should be carried out. Moreover, that the plate diameter (d A ) and the sample height (H) do not affect the measurement result with the use of cylinders with the heights of H30, H50 and H100, when the relation d A /D is within 0.5 ≤ d A /D ≤ 0.8 and the ratio D/H equals 2 and that it is possible to omit the value d A /D in a situation when soil is less cohesive and its moisture degree is 0.41-0.44 (Błażejczak and Dawidowski, 2017). After the correction was made, it should be assumed that the relation d A /D should be within: -0.5 ≤ d A /D < 0.8 for samples H30, -0.5 ≤ d A /D < 0.7 for samples H50.…”

“…While, it is not recommended to apply samples with the height of H100 with the use of a cylinder with diameter of 100 mm. The fact that the plates with the diameter of d A < 50 mm are omitted in the correction, despite the fact that according to the results from table 5 they do not cause the impact of the cylinder wall on the registered compaction resistance of a sample, results from the higher spread of the determined pre-compaction stress values (Błażejczak and Dawidowski, 2016a, 2016b, 2017. It may be justified with the fact that along with the decrease of the plate diameter, the processes taking place in the zone of impact of its edges may have even bigger share in the soil compaction resistance.…”

“…The research, which was carried out, proves that the relation of the plate diameter (d A ) to the cylinder diameter (D) should be within 0.5 ≤ d A /D ≤ 0.8. It was also stated that the plate diameter (d A ) and sample height (H) do not affect the measurement result when the relation d A /D is within 0.5 ≤ d A /D ≤ 0.8 and the ratio D/H is 2 (Błażejczak and Dawidowski, 2017) and that it is possible to omit the condition d A /D, when soil is less-cohesive and its moisture degree is ca. 0.41-0.44.…”