考虑模型和失效准则不确定性的自平衡桩基测试可靠度分析

An Analysis of Reliability of Self-balance Pile Test Considering Model and Failure Criteria's Uncertainty

自平衡桩基测试作为一种新型桩基测试在东南沿海已得到广泛应用,但其实际工程应用存在平衡点难于精确和转换系数不确定性问题,因此有必要对自平衡桩基测试模型可靠性进行研究。从模型和失效准则两大不确定性因素对可靠度影响进行了分析,建立了自平衡试桩模型在不同失效准则条件下的可靠度计算模式。同时结合工程算例分析表明:模型和失效准则不确定性会对桩基承载力确定产生显著的影响;不同失效准则确定自平衡桩基可靠度指标值是不一样的;不同失效准则和模型不确定性下得出的可靠度指标值基本符合国家规范要求,因此采用自平衡法来确定桩基极限承载力是可靠的。

As a new pile test, self-balance pile test is widely used in southeast coastal regions, but in actual projects, there are some problems such as balance point inaccuracy and the uncertainty of the conversion ratio. So it is necessary to study the reliability of self -balance pile test. Firstly, reliability is analyzed based on two uncertainty factors, and a theoretical formula is provided to calibrate the reliability of pile foundation by using a self-balance test. Then, based on projects, the results indicate that the model and failure criteria＇s uncertainty have an obvious effect on pile bearing capacity and that the reliability index can be obtained differently according to different failure criteria. Moreover, the calculating reliability index which considers different failure criteria meets the standard requirement and it indicates that using the self-balance test to determine the pile ultimate bearing capacity is reliable.