Shaft resistance of bored piles socketed in Malaysian granite

In this paper, an attempt is made to demonstrate the applicability of previously published models for granite formations in Malaysia. A programme of field testing was conducted to measure the axial response of bored piles, with a total of seven bored piles of diameter 1000–1500 mm constructed in decomposed granite, using techniques including the advancing of temporary casing and drilling slurry composed of bentonite fluids. These bored piles were subjected to static load testing in order to verify their integrity and performance, with the results of these load tests evaluated here. It was assumed that the strength of the soil was fully mobilised by the static loading test. The results revealed that the method proposed by Horvath and Kenny provided the best prediction of rock shaft resistance for decomposed granite. Based on the results obtained, it can be deduced that the proposed models based on sedimentary rocks are applicable to decomposed granite and that maximum rock shaft resistance can mobilise up to 1850 kPa in material of rock quality designation >60%.