砂砾石土渗透变形特性的应力状态相关性试验研究

渗透变形是砂砾石土地基及堤防结构破坏的常见形式之一。影响渗透变形的因素很多，其中颗粒级配及应力状态是最重要的两个因素。为研究土体应力状态大小对砂砾石土渗透变形临界水力梯度的影响，通过研制大直径渗透变形仪加载系统，完成了侧限条件下砂砾石土在0.1、0.3、0.6、0.9MPa铅直应力作用下的渗透变形试验。通过对实验结果的整理分析，结合考虑土体附加应力状态对临界水力梯度影响的理论研究，得到了渗透变形临界水力梯度随着应力状态的提高而加大的变化规律。通过对渗透变形试验过程中现象观察及渗透系数动态变化规律分析，建议了结合渗透变形试验中渗透系数变化过程线确定临界水力梯度的新方法。

Experiment study on the relevance between stress state and seepage failure of sandy-gravel soil

Seepage failure is one of the destructive type of levee structure and foundation in sandy-gravel soil stratum. There are many factors influence on seepage failure; the grain composition and the stress state are the most important factors. To explore the influence of stress state in the soil mass on the critical hydraulic gradient of seepage failure, a loading system for seepage failure experiment is developed. The seepage failure experiments of sandy-gravel soil sample, which is under lateral confining condition, are accomplished by exerting 0.1,0.3,0.6,0.9MPa vertical stress on the top of the sample. After the analysis of the experiment results and the theoretical study of the influence of stress state on critical hydraulic gradient, it indicates that the critical hydraulic gradient of seepage failure of the soil sample gradually increases with the increment of the stress state. Though analysis the relevance between the phenomenon of seepage failure and variation law of permeability coefficient, a new method for the determination of critical hydraulic gradient during seepage failure experiment is proposed.