摘要
为了评估不同失效准则对基桩可靠度的影响,传统的方法是引入失效准则偏差系数。然而目前所定义的失效准则偏差系数使得偏差系数和基本随机变量之间具有一定的相关性,直接将偏差系数的统计参数用于基桩可靠度分析是不尽合理的。为此,基于线性回归理论提出了新的失效准则偏差系数的定义,并采用Spearman秩相关系数方法检验了偏差系数和基本随机变量之间的相关性。采用算例分析了偏差系数和基本随机变量之间的相关性对基桩可靠度的影响。结果表明,传统的失效准则偏差系数的定义使得偏差系数和基本随机变量之间具有一定的相关性,提出的通用的失效准则偏差系数能够有效地消除这种相关性。偏差系数与基本随机变量之间的相关性对偏差系数的均值具有明显的影响,但对变异系数基本没有影响。此外,偏差系数与基本随机变量间的相关性对基桩可靠指标具有明显的影响,基桩可靠度分析中应该消除这种相关性。
A bias factor is commonly used to account for the effect of differences in failure criteria on reliability of pile foundations. There are however, hidden statistical dependencies between the bias factor and the underlying random variables. It is not reasonable that the statistical parameters of bias factor are directly adopted for reliability analysis of pile foundations. This paper aims to propose a new generalized bias factor based on the linear regression theory. The Spearman rank correlation method is used to perform the check of statistical dependencies. Finally, a numerical example is investigated to illustrate the effect of such statistical dependencies on reliability of pile foundations. The results indicate that the statistical dependencies between the bias factor defined by previous studies; and the underlying random variables can be removed using the proposed definition of bias factor. Such dependencies have a significant influence on the mean of bias factor, but they have hardly influence on the coefficient of variation of bias factor. Reliability indexes are also influenced by such dependencies. Therefore it is recommended that such dependencies be removed so that reliability of pile foundations can be evaluated in a more rational way.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2008年第3期633-638,共6页
Rock and Soil Mechanics
基金
国家十.一五支撑项目(No.2006BAB04A05)
