Statistical characteristics and probabilistic analysis of uncertain settlement of subgrade in permafrost regions

The settlement characteristics of permafrost subgrade are uncertain on account of the random thermal regime and mechanical parameters. This can affect the stability of permafrost foundation. In this study, the uncertain settlement behaviors of permafrost subgrade under global warming conditions are computed by Monte Carlo (MC) method. After that, the distributing fitting inspection of the samples of uncertain settlement characteristics are carried out. A probabilistic analysis methodology of the uncertain settlement of subgrade in permafrost regions is presented. The statistical characteristics and reliability of uncertain settlement for the subgrade center and shoulder are analyzed and predicted. This study presents a novel approach to estimate the stability of uncertain roadbed settlement. The results indicate that the uncertain settlement characteristics of embankment follow a normal distribution on the condition that significance level is 0.1. The reliability of subgrade center and subgrade shoulder varies with time, which imply railway operation have different risk in different seasons. The global warming can promote the thawing of permafrost foundations and it reduces the reliability. This study clearly clarifies the statistical characteristics and reliability of uncertain settlement characteristics of permafrost subgrade and the results can provide a reasonable basic data for the stability evaluation of permafrost subgrade.