Earthworks - Geotechnical Investigation and Design Tables - page 150

12.20 Maximum size of equipment based on permissible
vibration level

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Different weight rollers are required adjacent to buildings. This must be used with
a suitable offset distance.

•

The table is based on a permissible peak particle velocity of 10mm/second. Com-
mercial and industrial buildings may be able to tolerate a larger vibration level
(20mm/sec). Conversely, historical buildings and buildings with existing cracks
would typically be able to tolerate significantly less vibration (2 to 4mm/sec).

Table 12.20 Minimum recommended distance from vibrating rollers (Tynan, 1973).

Roller class Weight range Minimum distance to nearest building

Very light 1.25 tonne Not restricted for normal road use. 3 m <

Light 1-2 tonnes Not restricted for normal road use. 5 m

Light to medium 2-4 tonnes 5-10 m

Medium to heavy 4-6 tonnes Not advised for city and suburban streets 10-20 m

Heavy 7-11 tonnes Not advised for built up areas 20-40 m

12.21 Compaction required for different height of fill
•

The height of fill should also determine the level of compaction, and number of
passes.

•

The table below shows an example of such a variation, assuming similar materials
being used throughout the full height.

Table 12.21 Typical number of roller passes needed for 150 mm thick compacted layer.

Height of fill (m) Number of passes of roller for material type

Clayey gravel Sandy clay (CL), Clay, CH

(GC) clayey sand (SC)

<

2.5 m 3 3 4

2.5 to 5.0 m 4 5 6

5.0 to 10.0 m 5 7 8

•

The optimum compaction thickness depends on the type of equipment used.

12.22 Typical compaction test results
•

Granular material tends to have a higher maximum dry density and lower
optimum moisture content.

•

The optimum moisture content increases with increasing clay content.

12.23 Field compaction testing
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The sand cone replacement is a destructive test. For large holes or rock fill, water
or oil of known density is used.