Abstract: At present, the judgment criteria for the stability of the cohesionless soil are too broad, and the applicability to gravelly soil is still to be discussed. Therefore, based on the gravely soil seepage stability test data, the applicability of three commonly used judgment criteria for the cohesionless soil piping (H/F criterion, Wan & Fell criterion, and fine particle content criterion) to the determination of gravely soil piping is analyzed, and the main control factors affecting gravely soil piping are determined by combining data statistics and theoretical analysis. The commonly used criteria are improved and the criteria applicable to the determination of the gravely soil piping are proposed. The research results show that the common judgment criteria for cohesionless soil have a high rate of misjudgment for gravelly soil. The judgment criteria are affected by a variety of soil structure factors, and the main factors that affect the piping of the gravely soil are the nonuniformity coefficient, porosity, the proportion of particle size range, etc. When the nonuniformity coefficient of the gravely soil is greater than 80 and less than 20, the nonuniformity coefficient is the dominant factor that affects the piping of gravely soil. When the nonuniformity coefficient of soil is between 20 and 80, the proportion of different particle size ranges is the main influencing factor. The particle size distribution characteristic parameters used to calculate the boundary particle size of the judgment criteria change with the nonuniformity coefficient and the proportion of different particle size ranges.

Key words: Gravely Soils, Mathematical Statistics, NonCohesive Soil Criteria, Piping