考虑破坏作用的基桩承载力可靠度分析

Reliability analysis of bearing capacity of piles by considering their destruction

在静荷载试验中,基桩大都没做到破坏,桩中存在着"剩余承载力",桩基的可靠度指标被低估.利用贝叶斯统计方法,对承载力现场监测数据进行更新,并利用更新后的数据给出考虑基桩破坏的基桩承载力可靠度指标计算方法.通过算例分析表明:桩体做到破坏的静荷载试验次数越多,承载力的可靠度指标就越大;反之,桩体做到破坏的静荷载试验次数越少,可靠度指标就越小.因此,在评价桩基安全性时,考虑基桩破坏对可靠度指标的影响是十分必要的.

In static load test, most of piles are not destructed and a ＂surplus bearing capacity＂ is still there, so that the reliability index of pile foundation is underestimated. In this paper, Bayesian statistical method was employed to update the in-situ measured bearing capacity of piles. Meanwhile, based on the updated data, the reliability index was calculated by considering the destruction of the piles. It was shown by analyzing a computation case that the reliability index of bearing capacity would be larger and larger if the more tests of pile destruction were carried out. Contrarily, the smaller reliability index of bearing capacity would be obtained, in the opposite case. Therefore, when judging the safety of pile foundation, it is highly necessary to consider the influence of pile destruction on reliability of piles.