中文摘要：

自行设计模型槽进行垂直渗流下砂土管涌试验,通过精细化量测手段获取管涌发展中土体几何、水力学参数及颗粒运动特点,研究颗粒级配对管涌发生发展的影响,揭示管涌细观机理。管涌型砂土可动颗粒本身级配影响流失颗粒最大粒径及颗粒流失量在渗流方向上的分布情况,但对最终颗粒流失量影响不大;可动颗粒含量对砂土是否发生渗透破坏及潜蚀发展过程影响密切,临界细颗粒含量及存在的自滤过程是要考虑的。通过体视显微镜,从细观尺度揭示临界细颗粒含量的砂土在管涌过程中,可能产生自滤反滤现象而使系统自稳定,进一步揭示该机制是由于砂土在复杂的水土相互作用过程中形成层间系数D15/d85值符合自稳定的级配特点所致。研究表明,对级配分布较广,缺失中间粒径的管涌型砂土,要判别砂土是否会发生渗透破坏及其临界水力梯度大小,在采用经典公式或经验曲线判断的基础上,有必要针对实际工程土体的级配特性与实际水力学条件,开展复杂水土作用过程的试验论证。

英文摘要：

Combined with fine measuring equipment, vertical seepage sand piping tests were carried out through a self-designed model slot. The geometry and hydraulic parameters of soils and the particles movement characteristics are obtained during the tests to study the particle grading impact on piping development and to explore the mesoscopic mechanism of piping. In piping type soils, the gradation of movable particles does not affect the final particles loss fraction, while the maximum size and distribution law of loss particles are influenced. Whether the seepage failure occurs or not and the corrosion process are affected greatly by the movable particle content, and the critical content of movable particles and the self-filtering phenomenon should be considered fully. Through the stereo microscope, the self-filtering and self-stabilizing process internal the sand soil with critical content of fine particles is obtained during seepage from the mesoscopic view. It further reveals the interlayer value of D15/d85 resulting from interaction of soil and water is in line with the self-stabilizing gradation characteristics, which leads to the system self-stabilizing, In order to discriminate the seepage failure mode and critical hydraulic gradient magnitude in the case of sand with wide grade distribution and lack of middle size, it is necessary to carry out experimental demonstration for the complex interaction of soil and water, according to the accrual grading feature of engineering soils and the hydraulic conditions based on the traditional judgment formula or experience curves.