Study on the optimal test parameters for vibration compaction based on the control of physical-mechanical indicators

Purpose The indoor vibration compaction test ( IVCT ) was a key step in controlling the compaction quality for high-speed railway graded aggregate ( HRGA ), which currently had a research gap on the assessment indicators and compaction parameters. Design/methodology/approach To address these issues, a novel multi-indicator IVCT method was proposed, including physical indicator dry density ( ρ d ) and mechanical indicators dynamic stiffness ( K rb ) and bearing capacity coefficient ( K 20 ). Then, a series of IVCT s on HRGA under different compaction parameters were conducted with an improved vibration compactor, which could monitor the physical-mechanical indicators in real-time. Finally, the optimal vibration compaction parameters, including the moisture content ( ω ), the diameter-to-maximum particle size ratio ( R d ), the thickness-to-maximum particle size ratio ( R h ), the vibration frequency ( f ), the vibration mass ( M c ) and the eccentric distance ( r e ), were determined based on the evolution characteristics for the physical-mechanical indicators during compaction. Findings All results indicated that the ρ d gradually increased and then stabilized, and the K rb initially increased and then decreased. Moreover, the inflection time of the K rb was present as the optimal compaction time ( T lp ) during compaction. Additionally, optimal compaction was achieved when ω was the water-holding content after mud pumping, R d was 3.4, R h was 3.5, f was the resonance frequency, and the ratio between the excitation force and the M c was 1.8. Originality/value The findings of this paper were significant for the quality control of HRGA compaction.