![]() Reliable results depend on many factors Practice D 3740 provides a means of evaluating some of those factors.ġ.1 This designation outlines the procedures for obtaining undisturbed block (cubical and cylindrical) soil samples.ġ.2 Undisturbed block samples are obtained for laboratory tests to determine the strength, consolidation, permeability, and other geotechnical engineering or physical properties of the undisturbed soil.ġ.3 Two sampling practices are presented. Users of this practice are cautioned that compliance with Practice D 3740 does not in itself assure reliable results. Agencies that meet the criteria of Practice D 3740 are generally considered capable of competent and objective sampling. Note 1-The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. 3 The chain saw uses a special carbide-tipped chain. The chain saw has proved advantageous in sampling difficult soils, which are blocky, slickensided, or gravelly, or materials containing alternating layers of hard and soft material. Stress changes alone can cause enough disturbances in some soils to significantly alter their engineering properties. Usually the expansion is small in magnitude because of the shallow depth. This is the best available method for obtaining large undisturbed samples of very stiff and brittle soils, partially cemented soils, and some soils containing coarse gravel.Įxcavating a column of soil may relieve stresses in the soil and may result in some expansion of the soil and a corresponding decrease in its unit weight (density) or increase in sampling disturbance, or both. This method of sampling is advantageous where the soil to be sampled is near the ground surface. For this test both disturbed and undisturbed soil sample can serve the purpose.Undisturbed block samples are suitable for laboratory tests where large-sized samples of undisturbed material are required or where such sampling is more practical than conventional tube sampling (Practices D 1587 and D 6519 ), or both. Specific Gravity Test: This is used for determination of specific gravity of soil particles of both fine grained and coarse grained soils. This curve is useful in calculating the settlement of the soil layer. Oedometer is used to find out void ratio at the end of various stress level and hence curve is plotted. As disturbed specimens have a certain pre consolidation pressure, so for conducting the consolidation test undisturbed soil specimen is required. For this test the soil specimen should have water content greater than liquid limit of the soil but both disturbed and undisturbed soil sample can serve the purpose.Ĭonsolidation Test: This is used to determine the rate and magnitude of soil consolidation when the soil is restrained laterally and loaded axially. Shrinkage Limit Test: This is one of the Atterberg Limit test to find out the shrinkage limit of the soil. For this test both disturbed and undisturbed soil sample can serve the purpose. Hydrometer Test: This is used to determine the particle size distribution of fine-grained soils passing 75 µ sieve.
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