Influence of Degree of Saturation (DOS) on Dynamic Behavior of Unbound Granular Materials

The extensive application of natural unbound granular materials (UGMs) motivates studies into the mechanical properties of alternatives such as processed crushed rocks employed commonly as base or subbase layers. The rutting and settlement generated in base and subbase layers is widely restricted in many specifications and standards. In this research, the dynamic behavior including the resilient modulus (M-r) and the plastic strain (epsilon(p)) of the crushed rocks collected from Queensland in Australia will be tested by a series of repeated load triaxial test (RLT) tests to investigate the behavior of UGMs under the fluctuation of the degree of saturation (DOS) (59%-100%). In particular, the RLT specimens were prepared in the laboratory through proper gradation under optimum moisture content (OMC) and 100% standard proctor maximum dry unit weight. Results from the RLT tests showed that UGM specimens soaked at higher DOS generated lower resilient modulus and weaker resistance to heavy traffic volumes with significant accumulation of plastic strain. The M-r and epsilon(p) of the tested aggregates under different cyclic deviator stresses of 425 kPa and 625 kPa approximately linearly decreased and approximately linearly increased as the DOS increased with a certain number of cycles up to 50,000, respectively.

Automated summary

This research conducted repeated load triaxial tests on crushed rocks collected from Queensland, Australia to investigate their dynamic behavior, showing that UGM specimens soaked at higher degree of saturation exhibited lower resilient modulus and weaker resistance to heavy traffic. The resilient modulus and plastic strain of the tested aggregates decreased and increased approximately linearly as the degree of saturation increased with a certain number of cycles.