Abstract: Taking into account the uncertainties of the calculation model of bearing capacity and the load, with the reliability analysis method and the theory of probability and statistics, the calculation formulas of reliability indices for ultimate limit state (ULS) and serviceability limit state (SLS) are obtained respectively. Meanwhile, the linear relationship between reliability indices for ULS and SLS is presented. Finally, it is studied that the impact of stochastic behaviors of limiting tolerable settlement of pile head ( ) on reliability analysis for SLS. The following conclusions can be drawn from this study. First, the influences of soil type and pile type on the model factor for SLS are slight. Second, the reliability index for SLS decreases with an increase of the uncertainties from the bearing capacity calculation model and the load, although the decrease rate gradually diminishes. And the total variation in the reliability index for SLS is limited, which means that it is reasonable to ignore the influences of the uncertainties from the bearing capacity calculation model and the load on the reliability analysis for SLS in engineering practice. Third, the stochastic behaviors of have significant effect on reliability analysis for SLS. The model factor and reliability index for SLS both increase with an increase of . However, the variability of model factor for SLS decreases with increase of . The appearance of these conclusions is simply because the requirements of are different, but is not the result that the pile own properties have run into some changes. The research results would provide a reference for code amendment and engineering applications.

Key words: pile, reliability, ultimate limit state (SLS), serviceability limit state, limiting tolerable settlement