缺级粗粒土管涌类型的判别方法

Criterion of piping types for gap-graded coarse-grained soils

利用大型渗透变形仪,对不同最大粒径和细粒含量的缺级粗粒土的渗透破坏特性进行了系统的试验研究。研究结果表明,缺级粗粒土在细料含量小于30%的情况下都发生管涌型渗透破坏,基本符合前人提出的判别流土和管涌的准则。管涌破坏的类型可划分为发展性管涌和非发展性管涌两种,采用刘杰和康德拉且夫对发展性和非发展性管涌的判别方法都不能区分本次试验的管涌破坏类型。在康德拉且夫提出的判别粗粒土管涌类型的方法的基础上,考虑细料对粗料孔隙的填充程度及试样中缺级颗粒百分含量的影响,建立了缺级粗粒土管涌类型的判别式,为缺级粗粒土管涌类型的判别提供了新的思路和方法。

Large filtration erosion tests of many soil samples are performed to study the filtration erosion property of the gap-graded coarse-grained soils. The test results illustrate that piping will occur for the gap-graded coarse-grained soils if the fine-grained component less than 30%. This resutt accords with the criteria of boiling and piping proposed by previous researchers. The piping type can be divided into continuous and discontinuous piping. The criteria of continuous and discontinuous piping proposed by Liu Jie and Кондратьев are used to distinguish the two types of piping, but the test results disagree with their criteria. Based on the criteria of continuous and discontinuous piping proposed by Кондратьев, the criteria of continuous and discontinuous piping are proposed considering the filling degree of fine particles to the void of coarse-grained components and the influence of percentage of gapped particles. This criterion provides new idea and method to distinguish the two types of piping for the gap-graded coarse-grained soils.