基于长江中下游 16 个堤防工程粉质黏土渗透变形试验结果，通过 K-S 检验法，按照所有工程数据和单个工程数据分别进行临界比降的概率分布拟合检验，同时利用信息扩散法对单个工程的小样本临界比降的概率密度函数进行推断。分析表明，粉质黏土的临界比降服从对数正态分布，信息扩散法所得概率密度可较好拟合小样本参数的概率分布。研究成果可为堤防渗透稳定可靠性分析提供基础。

On the basis of seepage deformation test of silty clay from 16 levees in the middle and lower reaches of Yangtze River , the probability distributions of critical gradient are analyzed respectively from all data collected and data of single levee by K-S test method. Information spread method is also adopted to estimate probability density function of critical gradient of single levee with small samples. Results show that probability distribution form of vertical critical gradient of silty clay obeys the lognormal distribution, and by verification of K-S test, information spread method can be used in statistical analysis of probability distribution of stochastic parameters. Research results could offer the base for reliability analysis of levee seepage stability.