Compaction quality control of coarse-grained soils using dynamic penetration test results through correlation with relative compaction percentages

Document Type : Original Article

Authors

1 Faculty of Engineering, University of Qom, Qom, Iran

2 Dept. of Civil Engineering, Faculty of Engineering, University of Qom, Iran

3 Isfahan University of Technology, Faculty of Civil Engineering, Isfahan, Iran

Abstract

In this study, in order to control the compaction quality of the coarse-grained soils used in several road construction projects, the dynamic penetration test (DPT) has been conducted on the 50 locations using both the DPL and DPM. First, in order to obtain the results independently from the penetrometer type, the dynamic cone resistance (qd) values have been calculated in each location based on the hammer blows of both the DPL and DPM. Next, the average of qd values obtained by both the penetrometers, were correlated with the percentages of relative compaction (RC) in the same location obtained by performing the sand cone test on location and modified proctor test in laboratory. Accordingly, it was extracted a power correlation between the qd values and RC percentages, with the determination coefficient (R2) of about 0.64. Then, for considering the effect of soil grains size using the median particle size (D50), a more accurate power correlation was obtained which as a result, the R2 value enhanced to 0.89. Furthermore, in order to consider the soil vertical stresses caused by depth of testing as well as obtaining a normalized relationship, the qd values were divided by the vertical stresses and correlated with the RC percentages. Afterwards, for regarding the effect of soils grains size and also their gradation properties, this time by using the dimensionless coefficients of uniformity (Cu) and curvature (Cc), it was extracted an other normalized power correlation. The results showed that the R2 value enhanced from about 0.49 to 0.92.

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