Frequency Optimization of Vibratory Rollers and Plates for Compaction of Granular Soil

Sammanfattning: Vibratory rollers are commonly used for compaction of embankments and landfills. This task is time consuming and constitutes a significant part of most large construction and infrastructure projects. By improving the compaction efficiency, the construction industry would reduce costs and environmental impact.This research project studies the influence of the vibration frequency of the drum, which is normally a fixed roller property, and whether resonance can be utilized to improve the compaction efficiency. The influence of frequency on roller compaction has not before been studied but the concept of resonance compaction has previously been applied successfully in deep compaction of fills and natural deposits.In order to examine the influence of vibration frequency on the compaction of granular soil, small-scale compaction tests of sand were conducted under varying conditions with a vertically oscillating plate. Subsequently, full-scale tests were conducted using a vibratory soil compaction roller and a test bed of crushed gravel. The results showed that resonance can be utilized in soil compaction by vibratory rollers and plates and that the optimum compaction frequency from an energy perspective is at, or slightly above, the coupled compactor-soil resonant frequency. Since rollers operate far above resonance, the compaction frequency can be significantly reduced, resulting in a considerable reduction in fuel consumption, environmental impact and machine wear.The thesis also presents an iterative equivalent-linear method to calculate the frequency response of a vibrating foundation, such as a compacting plate or the drum of a roller. The method seems promising for predicting the resonant frequency of the roller-soil system and can be used to determine the optimum compaction frequency without site- and roller-specific measurements.