The field tests of 46 uplift-loaded belled piers were carried out at 7 gobi gravel sites in Gansu and Xinjiang

respectively. Based on the characteristics of the measured load-displacement curves

the L1-L2 method was used to obtain the ultimate bearing capacities and corresponding displacements. In addition

a normalized hyperbolic equation was applied to fit the measured load-displacement data. Accordingly

the fitting parameters of hyperbolic curve were provided and analyzed. A method was suggested for determining the allowable displacement and corresponding load by considering the uncertainties in the ultimate capacity model and the normalized load-displacement hyperbolic model. The uplift load-displacement curves of belled piers in gobi could be simplified to a generic load-displacement curve with three distinct stages: an initial linear stage

a nonlinear transition stage

and a final linear failure stage. The normalized load-displacement hyperbolic equation could be used effectively to fit the measured load-displacement data. The uncertainty in the normalized load-displacement hyperbolic curve could be studied by the corresponding fitting parameters of hyperbolic curve. The method to determine the allowable displacement and corresponding load would be more safety by considering capacity and displacement together.