A joint venture between Shimizu Corporation and Konoike Construction both from Japan, won the contract to build the flyover at Clocktower Roundabout in central Kampala. The flyover piers are founded on screw piles for which the JV has contracted a specialist installation expert from Japan.

SKJV asked EA Piling to design and execute a load test on a preliminary screw pile. In advance of the installation of the test pile EA Piling mobilised a Soilmec R620 rotary piling rig to install 1m diameter piles to provide the reaction force for the test. Ground conditions were harder than anticipated on the basis of the ground investigation, with the extremely stiff sand at the pile toes. Because of this drilling took longer than expected but the reaction piles were installed in plenty of time to allow curing of the concrete prior to the scheduled test. The reaction piles were installed to 18m. The test pile was designed to be installed to 14m but hit refusal at 12m.

EA Piling designed and fabricated a test set up using heavy duty steel beams tied into the reaction piles using threaded tensile bars. This was erected at the site using a 25Tonne capacity crane. The load was applied using a 500Tonne hydraulic jack and measured using a 500T load cell. Deflections were measured using displacement gauges installed on the pile head.

The loading schedule for the test was 2 cycles, the first to a working load of 230T and the second to 200% of the working load, 460T. At working load the measured deflection was just 5.8mm and at twice working load 21.5mm. The load test confirmed the pile design assumptions and installation of the working piles began almost immediately.

This is the largest load test to date in Uganda and the largest EA Piling have executed to date but as construction engineering in Kampala becomes more ambitious it might not hold that position for long.