Back-analysis of laterally loaded bored piles

Field lateral load tests were conducted on two single 1-5 m diameter large bored piles in Hong Kong. The test piles are embedded in superficial deposits and weathered rocks with various degrees of decomposition. In this paper, the pile load test results are interpreted and reported. A simple and rational method of back-analysis for long piles, using inclinometer data and assuming a fourth-order polynomial to represent the shape of soil reaction profile, is introduced. The method, requiring only simple spreadsheet-type operations, makes it possible to incorporate non-linear concrete behaviour in the back-analysis, and to deduce the p-y curves for future design of piles in similar ground conditions. In order to verify the rational method, an analysis is carried out using the back-analysed p-y curves, and the predictions are found to agree well with the measured pile head deflections. This proposed method demonstrates how p-y curves are back-analysed rationally for long piles embedded in complex ground conditions, in contrast to traditional back-analyses using recommended p-y curves for a uniform soil stratum