Field experimental study on optimal compaction parameters for vibratory compaction of soil–sandstone mixtures

Reliable selection of field compaction parameters is essential for improving the compaction quality and construction efficiency of soil–sandstone mixture subgrades. In this study, field rolling tests were conducted at the Tongzi Expressway site to evaluate the effects of loose lift thickness and rolling speed on vibratory compaction performance. The tested variables included loose lift thicknesses of 30, 40, and 50 cm, rolling speeds of 3 and 4 km/h, low- and high-amplitude vibration modes, and one to four roller passes. Acceleration sensors installed in the fill and on the roller drum were used to collect dynamic responses, while the sand-cone method was used to determine the degree of compaction. The relationship between the Compaction Meter Value (CMV) and conventional compaction indicators was also analyzed. The results show that, within the tested material, equipment, and parameter ranges, a 50 cm loose lift thickness combined with a rolling speed of 3 km/h produced comparatively favorable compaction performance. The average degree of compaction reached approximately 94% under low-amplitude vibration and 95% under high-amplitude vibration. The variation in CMV was generally consistent with that in the measured degree of compaction, suggesting that CMV can serve as a continuous monitoring indicator for field compaction quality control and parameter adjustment under the tested conditions.