01 July 1997
Table 5-1. Summary of load test results
13 Oct 1990
10 Oct 1990
e. Construction Events. A unilateral letter contract to construction the drydock was awarded to a
contractor 24 November 1989. Demolition of the existing facility was commenced, but was halted on
26 February 1990 because the Environment Assessment (EA) was deemed inadequate. With the signature
of a new EA on 31 May 1990, work was resumed. Indicator piles were driven for the onshore end of the
drydock. However, those planned for the offshore end were deleted to effect savings with it having been
decided that the piles were unnecessary. Pile driving commenced 25 April 1991. Although lower than
anticipated, blow counts were encountered, and the production piling was completed in June 1991.
Subsequent to an analysis of the situation, the contract was terminated on 8 July 1991. To remedy the
situation and complete the project, a supplemental test program was initiated and the tests under this
program were conducted in March 1992. These tests indicated that over time the piles had developed the
capacity to support the drydock.
5-2. ANALYSIS OF PRODUCTION PILE INSTALLATION.
a. Pile Driving Records.
(1) Pile Hammer. As was the case with the indicator piles, the rest of the piles were driven with the
Delmag D46-23 hammer, set for the 66 foot-kip energy setting. This corresponds to a ram stroke of 6 feet.
(2) Embedment Depth. The embedment depth of the piling is shown in figure 5-4; the average
embedment was 53 feet. The North group appears to have a slightly smaller embedment depth than the
South groups. The embedment depth for one pile in group N-3 was 44 feet, and several piles were
embedded about 50 feet; otherwise, these piles were driven to an embedment depth from 51 feet to
61 feet. Matching this depth range with the sampler blow counts from the borings in figure 5-3 indicates
that the boring N-value Nspt was expected to be at least 10 blows/foot.
(3) Penetration Resistance. The blow counts at final penetration for each group of piles,
figure 5-5, indicate that the penetration resistance at the toe depth of the North group is slightly less than
that for the South group. The slightly smaller values observed for the North group is consistent with the
slightly smaller embedment depth of the North group compared to the South group. Figure 5-5 also shows
that the final blow count decreases from a range of 6 to 37 blows/foot near the head wall down to 2 to
12 blows/foot near the far end offshore. The piles driven later in a group have a higher mean blow count
than those driven before. The mean blow count of the last pile driven in a group was generally twice that of
the first pile driven. There was no discernible difference in the driving due to batter.