Evaluation of Measurement Uncertainty for Specific Gravity Tests of Soil Samples

Measurement uncertainty for specific gravity tests of soil samples affects its reliability, and also influences the accuracy of porosity and saturation obtained by transforming specific gravity and other parameters. A pail of undisturbed silt was taken as the specimen. The specific gravity of soil samples was measured by the pycnometer based on Standard for soil test method (GB/T50123-1999). According to requirements of Uncertainty Evaluation and Denotation of the Measurement Results(JJF 1059-1999), we analyzes the factors affecting measurement accuracy, then builds a calculation model for the measurement uncertainty, and then evaluates the measurement uncertainty for specific gravity of soil Samples. The result shows that the contribution to the uncertainty of the measurement results comes mainly from weighing and inhomogeneity. The expanded uncertainty of measurement results of the specific gravity of soil samples is 0.005 under the proposed testing conditions.