Utility trench backfill compaction using vibratory plate compactor versus excavator-mounted hydraulic plate compactor

Excavator-mounted hydraulic plate compactors are widely used in utility trench backfill compaction due to their efficiency. However, there are industry concerns about the possibility of pipe damage due to the combination of static downward earth pressure exerted by the excavator arm and dynamic earth pressure induced by the excavator-mounted hydraulic plate compactor. This paper presents the results of a field study that aims to compare the performances of utility trench compaction using a conventional walk-behind vibratory plate compactor with a lift thickness of 200 mm (8 in.) and an excavator-mounted hydraulic plate compactor with a lift thickness of 200 mm (8 in.), 300 mm (12 in.), 450 mm (18 in.), and 600 mm (24 in.). Three types of pipes are used. The field test results indicate that the excavatormounted hydraulic plate compactor delivers compacted dry mass densities with a lift thickness of 200 and 300 mm comparable to the walk-behind vibratory plate compactor with a lift thickness of 200 mm; however, the excavator-mounted hydraulic plate compactor is not able to consistently achieve adequate compacted dry mass densities with a lift thickness of 450 and 600 mm. The excavator-mounted hydraulic plate compactor induces larger dynamic vertical earth pressures than does the walk-behind vibratory plate compactor. The excavator-mounted hydraulic plate compactor does not induce pipe damages in this study because the maximum strains in all pipes are smaller than 0.3%.