What is it about?

This technical paper summarises two full-scale field trials that used buried instrumentation in homogeneous soil to capture the effects of RDC in real-time to quantify the changes in stress imparted to the ground with increasing towing speed. This paper proposes that the energy imparted to the ground due to RDC should be considered in terms of work done, rather than the use of either gravitational potential energy, or kinetic energy (as is current practice).

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Why is it important?

Key findings or contributions to knowledge from this paper include: - Towing speed does influence the stress that is imparted to the ground - Energy imparted by RDC to the ground needs to be considered in terms of work done, which is due to the change in both potential energy in addition to the change in kinetic energy. - Describing the energy imparted to the ground using total kinetic energy should be avoided as it overestimates the energy imparted to the ground. - Describing the energy using gravitational potential energy should also be avoided, as it is counter-productive for the impact rolling industry to develop specifications stipulating target towing speeds when the rollers are described solely in terms of their gravitational potential energy. - The maximum imparted energy delivered to the ground by the 4-sided impact roller was found to lie in the range between 22 kJ and 30 kJ, for typical towing speeds of 9-12 km/h.


Homogeneous soil conditions were used in the trials described in this paper to control other variables and isolate the effect of towing speed. There is a need for specifications to detail a target towing speed range for RDC. Based on the authors’ experiences, the optimum speed will vary depending on site conditions. To optimise the use of the 4-sided impact roller, a towing speed range of 10-12 km/h is recommended, which is consistent with the findings of the field trials reported in this paper.

Dr Brendan T Scott
University of Adelaide

Read the Original

This page is a summary of: Influence of towing speed on effectiveness of rolling dynamic compaction, Journal of Rock Mechanics and Geotechnical Engineering, February 2020, Elsevier, DOI: 10.1016/j.jrmge.2019.10.003.
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