BETONAC
SAW 180 vibrating roller
Six steel plates were embedded in the surface of each foundation to be dug out later so that settlement of foundation could be measured.
Rockfill was loaded at the quarry by Hitachi 11⁄2 cu.yd. face shovel and Michigan 4.5 cu.yd. loaders into 13/21⁄2 ton Hino dump trucks. On the first layer of Pad 1, the fill was dumped over the advancing edge of the layer but on the other pads it was dumped about 8 ft. back from the edge and dozed over. As far as possible the maximum size of rock was less than 2/3 of the layer.
The fill was compacted by the SAW 180 vibrating roller vibrating at 1,500 rpm in one direction only i.e. forward pass vibrating, backwards pass without vibration. Care was taken to line up the layers so that there was a minimum of over-lap. Each line was compacted twice before the roller was moved onto the next line.
The pads compacted wet had been sluiced with a volume of water equal to twice the volume of rock. The water was pumped from the River Pedu by a 10 in. centrifugal pump and di- rected at the rockfill through a 2 in. nozzle on a Stang 'Intelligiant' moni- tor. The nozzle pressure was about 3 kg/cm2 and flow was estimated at 2.75 cusecs.
Seven lines (10 ft. apart) of precise levels at 5 ft. centres were taken on each pad before compaction and then after every two passes of the roller. The level points were set in by theodo- lite and steel tape.
Four full truckloads of samples were weighed in Alor Star and then
42
fully graded at Pedu using sieves and 200 kg scales. These samples were col lected during the cutting of two wide trenches across the embankments to expose the profile.
Results
The results of the first layer of Pad A and all results on layer thicknesses
of less than 2 ft. 6 in. were ignored. The compaction results expressed as a cumulative percentage of the original layer thickness are listed in Table 1. The bracketted results show a rise of the surface and this pheno- mena may be accounted for by large boulders in the thinner layers tilting during compaction.
From table 1, four graphs number- ed 1, 2, 3 and 4 have been prepared. Graphs 2, 3 and 4 of percentage settle- ment v thickness of layer gave mini- mum settlements when the layer was approximately 4 ft. 6 in. thick. This may be accounted for by a tailing off of the effect of the roller below depths of 4 ft. 6 in, and increase in effect of dead weight of rockfill in layers great- er than 4 ft. 6 in.
Table 2 was prepared from Table 1 to show the percentage (of original layer thickness) difference of com- paction achieved at the same depth after the same number of roller passes by deducting the dry compaction cumulative percentage from the cumu- lative percentage of the same material compacted after sluicing.
Sieve analysis of rock samples gave a fairly even grading from 3 ft. to 100
TABLE 1
Summary Of Cumulative Compactive As Percentage Of Original Layer Depth
2.5' to 3.5' 3.5' to 4.5' 4.5' to 5.5' 5.5' to 6.5'
223
No. of Roller Passes
Layer Depth No. of
Obs.
2 4 6 8 10 12 14
16
18
20
9
7.5
10.0
11.2 12.6 13.4 13.7
7.7
8.3
9.7
4
4.7
8.3
9.1
11.3 (10.9) 11.9 10.6 (10.4) 11.5 4.9 6.5 6.6 8.0 8.3 8.7
14.7 12.2 11.8 9.7
15.5 (14.8) 16.0
12.9 13.2 13.3
12.2 12.8 12.9
10.0 10.2 10.3
Grade B
-
Rockfill Compacted Dry
2.5' to 3.5' 6 3.5' to 4.5' 4.5' to 5.5' 5.5' to 6.7'
Grade A
11.0
7
5.5
4
5.6
6.7
8
7.4
8.8
13.3 16.3 (15.8) 15.9 16.1
7.4 8.7 9.0 9.8 (9.6) 7.9 (7.8) 8.9 (8.7) 9.4 9.7 10.4 10.7
—
Rockfill Compacted After Sluicing
2
4
6
8
10
2.5' to 3.5' 3.5' to 4.5' 4.5' to 5.5' 5.5' to 6.5' 6.5' to 7.5'
4
6.9 9.7
11.5 11.7 13.4
10
4.2 6.9
(6.0) 6.9 8.2
5
6.6 7.3
8.2 8.8 10.4
12
7.8 9.0
4
7.9 8.7
10.6 11.3 12.2 9.3 10.0 10.8
Grade B
—
Rockfill Compacted After Sluicing
2
2.5' to 3.5'
9
3.5' to 4.5'
6
5.9
4.5' to 5.5'
10
6.0
5.5' to 6.5'
9
9.3
4 6 8 10 12 14 16 18
7.7 13.0 14.7 16.8 17.4 17.9 18.4 18.9 19.0 6.5 9.5 10.8 11.7 12.2 13.3 13.5 13.8 9.9 11.2 12.0 12.4 13.5 14.0 14.6 15.0 11.7 13.1 13.2 14.0 14.4 15.0 15.5 16.4
Far East BUILDER, July 1971