Probabilistic analysis of tunnel convergence on spatially variable soil: The importance of distribution type of soil properties.

Accurate prediction of tunnel convergence is important to ensure the stability of tunnel structures. Reliability analysis of tunnel convergence on spatially variable soils was performed based on Monte Carlo simulations. The Young's modulus of soils was shown to be spatially varied. The influence of the coefficient of variation, the vertical scale of fluctuation and the distribution type (i.e. beta distribution, gamma distribution and lognormal distribution) of soils on the tunnel convergence were systematically discussed. From measuring the mean and standard deviation of tunnel convergence, and the probability of exceeding some thresholds, it was found that the distribution type significantly influenced the results. The results were accompanied by a detailed analysis of the mechanisms of tunnel convergence in spatially random soils. [ABSTRACT FROM AUTHOR]