Optimization of vibratory equipment parameters for compaction of soils and bases of motor roads

Abstract

The setting of a roller vibration exciter on site still relies on trial rolling and operator experience, so that a factory preset results either in insufficient density in the lower zone of the lift or in weakening of the upper one. The purpose of the work is to substantiate the combination of vibration frequency, static moment of the eccentric masses and travel speed of a single-drum soil vibratory roller at which the required density is reached with the lowest specific energy consumption. An author’s two-mass model of the system «drum – sprung part – soil» with a unilateral contact constraint has been developed, supplemented by the Hertz-Belyaev contact problem and a kinetic equation of density accumulation; the calculation covers a sand-gravel mixture in a 0.50 m lift with a required degree of compaction of 0.98 and a tolerance of 0.02 under the current edition of SP 78.13330.2012. The specific energy consumption varies over the computational grid from 319 to 1698 kJ/m³ at a practically identical final degree of compaction, and the minimum, with the number of passes restricted to eight, falls on 33 Hz and a static moment of 3.8 kg·m; switching to this combination from the factory high-amplitude preset reduces energy consumption by 34,1% with a 12,5% loss of output. The depth of action and the energy efficiency are governed by different exciter parameters, so that a single roller setting for the whole embankment height remains unattainable, while the density difference between the sampling section and the bottom of the lift reaches 0.0199 and absorbs the whole tolerance.