EXPERIMENTAL DETERMINATION OF THE OPERATIONAL CHARACTERISTICS OF A MIXED ROLLER

FULL-SCALE COMPACTION TESTS WITH A PROTOTYPE ROLLER OF A MIXED TYPE (CONSISTING OF A VIBRATING ROLLER AND OF FOUR PNEUMATIC TYRES SUBJECTED TO A 3 TONNE LOAD) WERE CARRIED OUT TO DETERMINE OPTIMUM VALUES FOR VIBRATION PARAMETERS: MOMENT OF ECCENTRIC FORCES, FREQUENCY OF VIBRATION, RATIO OF THE SUSPENDED PARTS TO THAT OF THE VIBRATING PARTS, VALUES OF THE INFLATION PRESSURE OF THE PNEUMATIC TYRES AND OF THE SPEED OF TRANSLATION OF THE COMPACTOR. IT WAS SHOWN THAT COMPACTION CARRIED OUT WITH THIS TYPE OF ROLLER IS MORE SATISFACTORY THAN COMPACTION WITH A VIBRATING ROLLER. EXPERIMENTAL SECTIONS WERE USED TO CONTROL THE COMPACTION OF NON-STABILIZED PAVEMENT LAYERS AND LAYERS STABILIZED WITH HYDRAULIC BINDERS. A SIMPLE MATHEMATICAL MODEL WAS USED TO DESCRIBE THE DYNAMIC BEHAVIOUR OF THE VIBRATING ROLLER ON THE SOIL; THE THEORETICAL CONCLUSIONS REACHED WITH THIS MODEL ARE COMPARED WITH EXPERIMENTAL RESULTS.