土坝渗透稳定可靠性分析方法及应用

采用确定性分析方法分析土坝渗透稳定的理论和方法已经较为完善,但它由于没有考虑坝体材料参数的变异性,因此得出的安全分析成果并不能完全可靠地表征其安全性。利用概率与统计的方法对土坝渗透稳定进行可靠性分析则可考虑坝体材料等一些不确定因素对土坝的渗透稳定影响。首先利用统计方法对坝体材料物理参数进行分析,得出了参数的概率分布类型,然后运用可靠性分析原理,构造土坝渗透破坏功能函数,分析土体有效重度、内摩擦角,坝体、坝基材料渗透系数对功能函数的影响,并采用几何法对坝体渗透破坏可靠指标进行计算,得出坝体发生渗透破坏的概率。利用上述方法对一土坝渗透稳定进行了分析。结果分析表明,坝体渗透破坏的概率随着土体有效重度和内摩擦角变异性的增加而增加,并且土体内摩擦角的变异性对坝体渗透破坏的影响较大,坝体渗透变异性对坝体渗透破坏的影响较大;另外,随着库水位的升高,坝体发生渗透破坏的概率也显著增加。

Reliability analysis on seepage stability of earth dams and its application

The deterministic methods widely used to evaluate seepage stability of earth dams were perfect.But the safety of earth dams could not be indicated reliably by the results of safety analysis due to the incomplete consideration of variation of parameters of dam material.In the seepage stability analysis of earth dams using probabilistic and statistic methods the uncertain factors of dam materials could be taken into account.First,the probability distribution of physical parameters of dam materials was obtained by use of the statistic methods.Then the principle of reliability analysis was used to construct the function of seepage failure of earth dams,and the effect of effective unit weight and angle of internal friction of soil,seepage coefficient of dam body and foundation were also analyzed.The geometric methods were adopted to calculate the reliability index of seepage failure of earth dams,furthermore the seepage failure probability of earth dams was also obtained.Taking one earth dam for example,the method mentioned above was used to analyze the seepage stability of earth dams.It was shown that the great variation of effective unit weight and angle of internal friction of soil could result in the increase of seepage failure probability of earth dams,the effect of variation of angle of internal friction of soil was greater,and the seepage failure probability of earth dams was sensitive to variability of dam seepage.In addition,the increase of water level in reservoir would also induce great increase of seepage failure probability of earth dams.