铁路桥梁浅基础设计变量的不确定性分析
Analysis on the uncertainty of design variables of shallow foundation in railway bridge

设计变量不确定性的计算分析是修订基于可靠性理论设计规范的基础工作。对铁路桥梁浅基础采用以可靠性理论为基础的概率极限状态设计方法进行研究，将设计中各种设计变量的不确定性进行了归纳、整理。在此基础上，讨论荷载效应和地基土极限承载力的不确定性，确定永久作用和可变作用中几种主要荷载的无量纲化系数的均值、均方差和变异系数，并根据有关资料和可靠性原理推导地基土极限状态条件下的宽、深修正系数和地基土抗力变异系数的计算表达式。研究成果可为可靠性理论规范的改进和修订提供参考和借鉴。
The calculation and analysis on the uncertainty of design variables is a basic work for revising some specifications in reliability-based codes. In this paper, a study on shallow foundation of railway bridge was carried out by using the probabilistic limit state design method based on the reliability theory, and the uncertainty for a series of design variables in engineering design was summarized and classified. On this basis, the uncertainty of the load effect and the ultimate bearing capacity of the foundation soil were mainly discussed. The mean value, the variance and the variation coefficient were determined for the dimensionless coefficients of the permanent and variable loads. The related data and the reliability principle were used to deduce the expressions for the correction coefficients of width and depth, and the variation coefficient of soil resistance under the limit state of the foundation soil. The results can be referenced and utilized for the revision of the reliability-based codes