Estimating side resistance of bored pile in residual soils

Bored piles are extensively used as foundation in Singapore residual soils. However, traditional design of bored piles is based on properties of clays, sands, or rocks. In addition, bored piles are design to rely on base resistance (Q_b) despite the fact that side resistance's (Q_s) contribution towards axial capacity is higher at the working load. Using instrumented pile load test results from Bukit Timah Granite and Jurong Formation residual soils, correlations for unit side resistance (f_s) with SPT-N and soil properties were developed. The estimates of side resistance (Q_s-est) from the developed correlations were compared with Q _s-est from recommendations by other researchers which have been adopted in practice. Based on the comparison, the design of bored piles installed in Singapore residual soils can be optimized using the developed correlations.