Abstract
Compaction is an important standard in evaluating the quality of earth filling work. The EDG, an electrical density gauge, is a new type of fast and nondestructive compaction detection equipment. It is used to test the dry density and water content of the soil by establishing a soil calibration model while the accuracy of measurement is mainly based on the precision of equation of calibration model. In this paper, the factors affecting the accuracy of the soil calibration model were studied by an indoor calibration test, and soil samples were prepared to verify the accuracy of the soil calibration model. The test results showed that the dry density range, water content range, and sample quantity 13 samples of soil had a significant influence on the correlation coefficient (R2) of the equation of the soil calibration model. In addition, when using the calibration model with different sample numbers and sample combinations but similar correlation coefficients to test multiple groups of density and moisture content, there are also differences in the expected value and standard deviation of the error probability curve of the test results. In the engineering practice, the reasonable sample quantity was determined by the applicable range of dry density and water content obtained from the measurement error analysis of the soil calibration model.
Highlights
Compaction, an important standard in evaluating earth filling works, is calculated by testing the dry density of soil obtained from the conversion of the wet density and water content
When the number of samples used to establish the θ v -R/C calibration equation increased, the relative error of water content measurements did not significantly change, and the expected value μ decreased, suggesting that the central tendency position of the measurements was close to the point 0; the standard deviation σ did not significantly change, indicating that the dispersion of the measurements had little change
When the number of samples used to establish the ρ-|Z| calibration equation was equal, namely 6 sample data and 12 sample data, the number of dry density groups was greater than the number of water content groups; both the expected value μ and the standard deviation σ were small, suggesting that this calibration equation was more advantageous for dry density measurements
Summary
Compaction, an important standard in evaluating earth filling works, is calculated by testing the dry density of soil obtained from the conversion of the wet density and water content. Traditional soil density test methods include the cutting ring method and the sand replacement method; the traditional soil water content test methods aregenerally the drying method or alcohol burning method. The results of these test methods areaccurate and easy to understand, but they are time-consuming and arduous. Based on the test result of density and water content of the soil using EDG, the cutting ring method, and drying method, the influence of the density range, water content range, and sample quantity of soil samples on the R2 was studied.
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