黏粒含量对泥石流源区砾石土体强度影响的实验研究

摘要

The clay content of the gravel soil from the upstream area of a debris flow has significant influence on the pore pressure and shearing strength. This is a problem that has to be solved in studying the debris flow initiation mechanism. Based on the three-axial experiment, this paper studies the relationship among the shearing strength, pore pressure, collapsibility and clay content of the sample from Jiangjia ravine of Dongchuan in Yunnan of China. The experiment indicates that (1) when the clay content is 3. 75%~7. 50%, the collapsibility of the sample is greater and when it is 5%, that of the sample is the maximum; (2) in the UU experiment, the pore water pressure of the samples with 3. 75%~7. 50% clay content has the greater increase, and in the CD experiment, the pore water pressure of the sample with 12. 5% clay content has the greater increase; (3) the gravel soil with 5% clay content is the easiest to demolish; (4) under the same conditions of rainfall and gradient, the gravel soil with 3. 75% ~ 7. 50% clay content is most likely to motivate a large-scale devastative debris flow.%泥石流源区砾石土的黏粒颗粒含量对砾石土孔隙水压力和强度的影响是泥石流形成机理中的重要问题之一.采用室内静三轴实验研究云南东川蒋家沟支沟大凹子沟源区的砾石土体强度、孔隙水压力、湿陷性与黏粒颗粒含量的关系,发现黏粒的质量分数在3.75％～7.50％范围内的砾石土试样湿陷性较大;黏粒的质量分数为5％左右的砾石土湿陷性最大；黏粒的质量分数在3.75％～7.50％范围内砾石土试样在不固结不排水剪切过程中孔压上升较高;黏粒质量分数在12.5％的砾石土试样在固结排水剪切过程中孔压上升较高；黏粒的质量分数为5％的砾石土强度最低,在相同条件下最容易被破坏.结合实验结果与泥石流启动机理分析,认为中等黏粒含量(质量分数为3.75％～7.50％)的砾石土在相同降雨和坡度条件下,最易启动形成泥石流.