Proposed test pile locations
| Test pile ID | Location with technical justifications | Representative abutment/pier and test pile boreholes |
|---|---|---|
| 1 | Test Pile #1 located at the southern end of the new bridge alignment (i.e., near Abutment A). The location lies within the Granton Fault zone extending from the southern abutment to Pier 7. Piles are expected to be socketed into the tertiary sedimentary breccia unit. This unit is indicated to be extremely to highly weathered, very low strength to the soil like strength (i.e., hard soils) at depths. Note that a narrow horst (fault block) of high strength Permian Sandstone appears to run sub-parallel to the bridge alignment intercepting some of the footprints of Pier 3 and Pier 5. These piers founded in Permian Sandstone are expected to perform exceptionally well from geotechnical capacity standpoint therefore this geological unit is not targeted. | Abutment A (South) to Pier 7 and BH22-97 with borehole termination level of RL-83.2 m AHD |
| 2 | Test Pile #2 located at ≈9–10 m south-east of P8R where the pile is expected to be embedded into a sequence of estuarine clay/silt, tertiary conglomerate, and finally socketed into Tertiary Sedimentary Breccia, siltstone, and sandstone. The rock units at this test pile location are the predominant contributors to the geotechnical axial capacity of the production piles from Pier 8 to Pier 13. | Pier 8 to Pier 13 and BH22-98 with borehole termination level of RL-101.6 m AHD |
| 3 | Test Pile #3 located in front of Abutment B. Basalt breccia on the north riverbank are generally of medium to high strength rocks, and the underlying basalt flows are of high to very high strength. From current geological interpretation, the basalt breccia and basalt flows from the North Abutment to Pier 14. Rock socket piles within this zone rely predominantly on the basalt breccia layer to provide geotechnical capacity. The test pile at this location will inform both design parameters, pile deformation behaviour, and installation (including production rate) predominantly in the basalt breccia layer. | Pier 14 to Abutment B (North) and BH22-99 with borehole termination level of RL-39.8 m AHD |
| 2A | Test Pile #2A located at ≈9–10 m northeast of P9R where the pile is expected to be embedded into a sequence of estuarine clay/silt, quaternary alluvial gravel/cobbles, tertiary sedimentary breccia, siltstone, and sandstone, and finally socketed into tertiary conglomerate. The rock units at this test pile location are the predominant contributors to the geotechnical axial capacity of the production piles from Pier 8 to Pier 13. | Pier 8 to Pier 13 and BH22-100 with borehole termination level of RL-110.4 m AHD |
| Test pile | Location with technical justifications | Representative abutment/pier and test pile boreholes |
|---|---|---|
| 1 | Test Pile #1 located at the southern end of the new bridge alignment (i.e., near Abutment A). The location lies within the Granton Fault zone extending from the southern abutment to Pier 7. Piles are expected to be socketed into the tertiary sedimentary breccia unit. This unit is indicated to be extremely to highly weathered, very low strength to the soil like strength (i.e., hard soils) at depths. Note that a narrow horst (fault block) of high strength Permian Sandstone appears to run sub-parallel to the bridge alignment intercepting some of the footprints of Pier 3 and Pier 5. These piers founded in Permian Sandstone are expected to perform exceptionally well from geotechnical capacity standpoint therefore this geological unit is not targeted. | Abutment A (South) to Pier 7 and BH22-97 with borehole termination level of RL-83.2 m |
| 2 | Test Pile #2 located at ≈9–10 m south-east of P8R where the pile is expected to be embedded into a sequence of estuarine clay/silt, tertiary conglomerate, and finally socketed into Tertiary Sedimentary Breccia, siltstone, and sandstone. The rock units at this test pile location are the predominant contributors to the geotechnical axial capacity of the production piles from Pier 8 to Pier 13. | Pier 8 to Pier 13 and BH22-98 with borehole termination level of RL-101.6 m |
| 3 | Test Pile #3 located in front of Abutment B. Basalt breccia on the north riverbank are generally of medium to high strength rocks, and the underlying basalt flows are of high to very high strength. From current geological interpretation, the basalt breccia and basalt flows from the North Abutment to Pier 14. Rock socket piles within this zone rely predominantly on the basalt breccia layer to provide geotechnical capacity. The test pile at this location will inform both design parameters, pile deformation behaviour, and installation (including production rate) predominantly in the basalt breccia layer. | Pier 14 to Abutment B (North) and BH22-99 with borehole termination level of RL-39.8 m |
| 2A | Test Pile #2A located at ≈9–10 m northeast of P9R where the pile is expected to be embedded into a sequence of estuarine clay/silt, quaternary alluvial gravel/cobbles, tertiary sedimentary breccia, siltstone, and sandstone, and finally socketed into tertiary conglomerate. The rock units at this test pile location are the predominant contributors to the geotechnical axial capacity of the production piles from Pier 8 to Pier 13. | Pier 8 to Pier 13 and BH22-100 with borehole termination level of RL-110.4 m |
Test Pile #2A was added to the test piling activities due to concerns around the validity of the results of Test Pile #2. The reasoning for the additional test pile is provided below
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