考虑参数和模型不确定性的基桩承载力可靠度

Reliability of bearing capacity of pile in consideration of parameters and model′s uncertainty

对参数和模型的不确定性因素进行了分析,若不能正确地考虑参数和模型不确定性对基桩承载力的影响,则桩的安全性会被低估.为此,引入修正因子对承载力的试计比和变异系数进行修正,消除了参数和模型不确定性对可靠度分析产生的影响,并给出了修正后可靠度指标的计算方法.算例分析表明:修正后的可靠度指标大于原始可靠度指标,桩的安全性被正确估计,证明了提出方法的有效性.

There are two types of uncertainties affecting the bias factors and coefficients of variance of bearing capacity of pile,i.e.,the parameter and model uncertainty,which have great contributions to reliability analysis of pile.The two uncertainties were adequately analyzed,and the results indicate that the safety of pile may be underestimated if parameter and model uncertainty were not reasonably addressed when evaluating ultimate bearing capacity of pile.Therefore,a modification factor was introduced to calibrate the bias factors and coefficients of variance for bearing capacity,thus overcoming the effect caused by the two uncertainties to reliability analysis,and the modified calculation formula of reliability was presented.The results through the case study show that modified reliabilities are larger than primary reliability,which demonstrates that the safety of pile is reasonably estimated proving the validity of the presented method.