Abstract
Rolling dynamic compaction (RDC) is typically used for improving ground in situ or compacting fill in thick lifts. In many project applications, the effects of RDC are verified by way of testing that is undertaken pre- and/or post-compaction. This study presents results from a full-scale field trial that involved placing an earth pressure cell (EPC) and accelerometers at a depth of 0·7 m within a 1·5 m thick layer of homogeneous sandy gravel to measure the response to RDC in real-time. Double integration of acceleration–time data enabled settlement to be inferred, while the EPC measured the change in stress due to impact. The maximum change in vertical stress recorded over the 80 passes undertaken was approximately 1100 kPa. During a typical module impact, the loading and unloading response occurred over a duration of approximately 0·05 s. The acceleration response of RDC was measured in three orthogonal directions, with the vertical accelerations dominant.
Highlights
Rolling dynamic compaction (RDC) imparts energy to the ground through the use of a heavy, non-circular module that falls to impact the ground
A limitation with such a prediction is that a RDC module that is towed across the surface impacts the ground in a different manner to a dynamic compaction pounder that is a function of mass, drop height and vertical acceleration due to gravity
Heyns (1998) and McCann & Schofield (2007) both noted that an increase in the magnitude of decelerations is commonly measured with increasing passes, as the surface soil stiffness increases. This finding is consistent with the work of Clifford (1978), who observed that the module drop height increases as the ground surface becomes harder; the cross-sectional area of the module that is in contact with the ground changes with drop height due to the geometry of the rounded corners and how far they embed in the ground
Summary
Rolling dynamic compaction (RDC) imparts energy to the ground through the use of a heavy, non-circular module that falls to impact the ground. A limitation of many past field investigations to verify the effects of RDC is that testing is typically performed pre- and/or post-compaction Such investigations often serve their intended purpose for determining if a project specification has been met (or otherwise) but they do not capture the dynamic effects of a heavy module impacting the ground in real-time. The use of module-mounted accelerometers has proven useful in identifying less stiff nearsurface soils that typically exhibit lower decelerations (McCann & Schofield, 2007); there is no guarantee that measuring the response of an impact roller as it passes over the ground surface gives a true indication of the soil response below the surface. Mooney & Rinehart (2007) carried out a field investigation using a smooth drum vibrating roller They performed multiple passes across test areas comprising both heterogeneous and homogeneous soils. Published with permission by the ICE under the CC-BY license
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