Field Study of Compaction Quality Control Parameters and Compaction Mechanism of Large Particle Size Stone-filled Embankment

Road embankments in the mountains of Southwest China are typically constructed using locally available block stones left over from cutting and tunnel blasting. However, due to the lack of reliable compaction quality control standards, poor filling quality of stone-filled embankments frequently occurs. The effective control of compaction quality for each paving layer is crucial to the filling quality control of whole stone-filled embankments. This paper describes a series of field studies to establish a compaction quality control system and analyse the compaction mechanism. Different types of compaction quality control indices were proposed, and their reliability was verified. Based on the established compaction quality control system, economical and efficient compaction quality control parameters that satisfy filling quality control and rapid mechanized construction were obtained. Meanwhile, the compaction mechanism of stone-filled embankments was analysed, and the analysis results of the compaction mechanism also verified the reliability of the obtained compaction quality control parameters. The field study results show that (1) there is a strong linear correlation between the static soil pressure increment (cumulative surface settlement ratio) and the compacted density in block stone fillers; (2) the reliable and efficient compaction quality control parameters are 420 kN of roller excitation force, 650 mm of control particle size of block stone fillers, 1000 mm of compacted thickness, and 8 of number of roller passes; (3) the compaction energy propagates up to the 1.0–1.2 m depth into the large particle size block stone lift under the action of 420 kN of roller excitation force; and (4) the vertical displacement of block stone fillers caused by compaction energy propagation is larger than its horizontal displacement. The filled testing program research results provide theoretical and technical support for the filling quality control of large particle size stone-filled embankments in mountain expressways.