Roller compaction of rock-fill with automatic frequency control

Abstract

A new intelligent compaction method for vibratory soil compaction rollers that automatically and continuously adjusts the vibration frequency to obtain resonance in the coupled roller–soil system was evaluated in full-scale field tests on a 1 m high rock-fill embankment. This method has been called automatic frequency control (AFC). Compacting at the resonant frequency results in maximised deformations in the soil by optimising the dynamic behaviour of the system and improving the interaction between the drum and the soil. The embankment was also compacted conventionally at a fixed standard frequency in order to quantify the difference between the two methods. Applying AFC resulted in a higher degree of compaction of the embankment layer. The effect was most significant at the top of the embankment, where considerable compression was obtained – in contrast to the very loose material resulting from conventional compaction – thus eliminating the need for subsequent static passes. Spot tests showed a considerably stiffer embankment surface after a high number of passes using AFC. Other observed benefits of AFC include a more homogeneously compacted embankment, which benefits long-term behaviour, up to 15% reduced fuel consumption, reduced environmental impact and less machine wear.