Study on the dynamic characteristics of geogrids combined with rubber particles reinforced with calcareous sand

Reinforced calcareous sand is increasingly recognized as a promising roadbed filler. This study evaluated the effects of different reinforcement methods, rubber content, dynamic stress amplitude, and loading frequency on calcareous sand through stress controlled undrained triaxial tests, and studied the dynamic characteristics and particle crushing of reinforced calcareous sand. The results showed that geogrid reinforcement increased the occurrence of particle fragmentation in calcareous sand and had the ability to resist deformation of rubber–calcareous sand mixtures, but the addition of rubber retarded particle fragmentation. In the case of geogrid reinforcement, the increase in rubber particle content from 0 to 10% corresponded to a 23.9% decrease in relative particle fragmentation. In the case with rubber particle reinforcement only, after 1000 cumulative loading cycles, the cumulative axial strain of the specimens increased 2.9 times when the rubber content was increased from 10 to 30%; the cumulative axial strain increased 60.7% when the amplitude of the dynamic stress was increased from 40 to 80 kPa; and the cumulative axial strain decreased 1.7% when the loading frequency was increased from 0.5 to 2 Hz, from 2.46 to 1.825%. The results of the study can provide reference and guidance for practical engineering.