3.3 Compaction The standard compaction tests may be used to establish the field density. For fills that will later support any structure it is usual to perform compaction tests to establish the required compacted density and optimum moisture content(OMC) for the field soil. Field density tests(quality control)are then performed to ensure the desired unit weight yis obtained. With compaction control,the fill is often of better quality than the underlying soil. The underlying soil will undergo settlement of varying magnitude depending on its characteristics and the depth of fill Dil which produces a settlement/consolidation pressure of yD 淘
3.3 Compaction ▪ The standard compaction tests may be used to establish the field density. ▪ For fills that will later support any structure it is usual to perform compaction tests to establish the required compacted density and optimum moisture content (OMC) for the field soil. ▪ Field density tests (quality control) are then performed to ensure the desired unit weight γis obtained. ▪ With compaction control, the fill is often of better quality than the underlying soil. ▪ The underlying soil will undergo settlement of varying magnitude depending on its characteristics and the depth of fill Dfill which produces a settlement/consolidation pressure of γDfill
3.3 Compaction Settlement will be nonuniform if the fill depth varies or if the site consists of both cut and fill. Settlements may be of long duration unless special steps are taken to speed up the process such as overfill(or preloading)to increase the settlement pressure and/or installation of drainage to speed consolidation. Compaction of cohesive soils can be accomplished using sheep- foot or rubber-tired rollers.Lifts are commonly 150 to 200 mm thick Compaction of cohesionless soils can be accomplished using smooth wheel rollers,commonly with a vibratory device inside,so the compaction is a combination of confinement,pressure,and vibration.Lift depths up to about 1.5 to 2 m can be compacted with this equipment. In confined spaces,it is necessary to use hand-powered equipment for compacting the soil.This requirement reduces the lift thickness so that if density has been specified,lift thicknesses should not exceed 75 to 100 mm
3.3 Compaction ▪ Settlement will be nonuniform if the fill depth varies or if the site consists of both cut and fill. ▪ Settlements may be of long duration unless special steps are taken to speed up the process such as overfill (or preloading) to increase the settlement pressure and/or installation of drainage to speed consolidation. ▪ Compaction of cohesive soils can be accomplished using sheepfoot or rubber-tired rollers. Lifts are commonly 150 to 200 mm thick. ▪ Compaction of cohesionless soils can be accomplished using smooth wheel rollers, commonly with a vibratory device inside, so the compaction is a combination of confinement, pressure, and vibration. Lift depths up to about 1.5 to 2 m can be compacted with this equipment. ▪ In confined spaces, it is necessary to use hand-powered equipment for compacting the soil. This requirement reduces the lift thickness so that if density has been specified, lift thicknesses should not exceed 75 to 100 mm
