加筋土路堤内部稳定的可靠指标分析

Reliability index analysis of internal stability of reinforced embankment

为了完善加筋土路堤可靠性设计方法,运用蒙特卡罗法对设计参数随机变量与加筋土路堤内部稳定可靠指标的关系进行分析。通过数值计算发现,密度越小,粘聚力、内摩擦角、筋材抗拉强度和筋土似摩擦系数越大,加筋土路堤内部稳定性越好,加筋土路堤内部稳定可靠指标对设计参数变异性均较敏感,除内摩擦角外,其余设计参数的不同概率模型以及不同公路等级设计荷载对加筋土路堤内部稳定性影响不大。因此,在加筋土路堤可靠性设计中,建议采用密度小、粘聚力和内摩擦角大的填料以及高强度筋材,并且重点考虑内摩擦角的变异水平。当无法准确确定设计参数所服从的概率模型时,建议假定填土的密度服从极Ⅰ型分布,而粘聚力、内摩擦角、筋材拉力和筋土似摩擦系数服从正态分布,所得到的结果偏于安全。

In order to perfect the reliability design method of reinforced embankment, Monte- Carlo method was adopted to analyze the relations between the design parametric random variables and internal stability reliability index of reinforced embankment. Analysis result indicates that the internal stability is better when the density is lower, and the parameters, such as the cohesion, internal friction angle, geosynthetics tensile strength and pseudo-friction coefficient, are larger. The internal stability reliability index is sensitive to the variation coefficients of the design parameters. Except the internal friction angle, other different probabilistic models of the design parametric random variables and the design loads of different highway classes have little influence on the internal stability. Perhaps the internal stability is improved while light filler with high cohesion and big internal friction angle and high strength geosynthetics are used in the reliability design. The reliability tend to be safe while filler density accords with extremal type I largest distribution, the cohesion, internal friction angle, geosynthetics tensile strength and pseudo-friction coefficient accord with normal distribution. 3 tabs, 9 figs, 10 refs.