BARRETTE BI-DIRECTIONAL PRELIMINARY LOAD TEST UP TO 148750 kN-Paper

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The paper reports a preliminary bi-directional static load test on a 52.5 m-long, 2.8 × 1.2 m barrette for a high-rise tower in Dubai Business Bay. The project foundation comprises 56 barrettes beneath a 5 m-thick raft; the maximum working load per barrette was 59,500 kN. The trial element was tested to 148,750 kN—2.5 times that working load—to assess its bearing capacity.<br /><br />Eight hydraulic jacks, each rated at 10,000 kN, were installed 32.5 m below the barrette cut-off level. Twelve strain-gauge levels measured load transfer along the shaft, while displacement instruments monitored movement. Four loading-unloading cycles were performed.<br /><br />At the maximum load, equivalent settlement at the barrette top was 35 mm. The barrette’s response remained practically elastic, with no clear failure or limiting skin friction reached. The measured unit base resistance was 1,550 kPa, but this was limited by the small toe displacement and therefore did not represent ultimate capacity. The results indicate that the barrette’s actual resistance is substantially greater than the maximum test load.<br /><br />Measured lateral skin friction ranged approximately from 90 to 550 kPa. Values were generally comparable to or above design estimates below 22.5 m from the cut-off level, but were lower than estimates in the upper portion and in the lowest 6 m above the base. Because the response remained far from failure, these measured values cannot be treated as ultimate resistances.<br /><br />The test demonstrated that a very high-capacity bi-directional test can be successfully applied to a rectangular barrette and provided valuable evidence supporting the foundation design.

Keywords

bi-directional static load test

barrette foundation

high-rise tower

Dubai Business Bay

bearing capacity

hydraulic jacks

skin friction

strain gauges

settlement measurement

load transfer