Document Type : Original Article
University of Qom, Faculty of Engineering, Civil Engineering Department, Qom, Iran
Isfahan University of Technology, Faculty of Civil Engineering, Isfahan, Iran
In this study, in order to control the compaction quality of the coarse-grained soils used in sub-base and base layers of several road construction projects, the dynamic penetration test (DPT) has been conducted on 50 locations using both dynamic penetrometer of light (DPL) and dynamic penetrometer of medium (DPM). First, in order to obtain the results independently from the penetrometer type, the dynamic cone resistance (qd) values were calculated in each location based on hammer blows of both DPL and DPM. Next, the average values of qd 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, 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.