摘要
冰碛土作为无定向排列的碎石类土,颗粒变化范围很广,具有特殊的结构特征和物理力学特征,在冰川融雪和暴雨激发下易形成泥石流。本次模拟试验通过PFC2D进行直剪试验模拟标定细观参数,再通过PFC3D,对变化含水率下冰碛土物源泥石流起动进行数值模拟。结果表明:离散元法能够很好地模拟冰碛土泥石流的起动、运动过程,能清晰的观察出不同含水率下各时刻的坡面状态;通过监测坡体不同位置的应力变化,得到冰碛土的坡面稳定和坡面破坏的临界含水率(10%),当含水量超过临界含水率,土体强度骤减,土坡逐渐失稳破坏;冰碛土在起动形成泥石流时,在坡顶、坡中和坡脚三个截面的土体结构控制分别为:提供咬合力的粗颗粒主控、粗细颗粒共同控制、提供黏聚力的细颗粒主控。离散元法具有良好的观测手段,对研究泥石流起动机理提供有力的依据。
Moraine soil is a kind of gravel soil with no directional arrangement,has a wide range of particle changes,and has special structural and physical and mechanical characteristics.It is easy to form debris flow under the excitation of glacier melting and heavy rain.This simulation experiment simulated and calibrated meso-parameters through PFC2 D direct shear test,and then simulated the debris flow starting of moraine soil source by PFC3 D.The results showed that:The discrete element method can simulate the starting and moving process of moraine mud and stone flow well,and can clearly observe the slope state at different water content;The critical water content(10%)of moraine soil was obtained by monitoring the stress change at different positions of slope body.When the water content exceeds the critical water content,the soil strength decreases suddenly,and the soil slope is gradually unstable and destroyed.When the moraine soil starts to form debris flow,the control of soil structure at the top,the middle and the foot of the slope is as follows:main control of bite force of coarse particles,Co-control of coarse and fine particles,main control of fine particles providing cohesion.The discrete element method is a good observation method,which provides a strong basis for studying the starting mechanism of debris flow.
作者
樊圆圆
宋玲
孙雯
FAN Yuanyuan;SONG Ling;SUN Wen(Shihezi University,Shihezi 832000,China)
出处
《干旱区资源与环境》
CSSCI
CSCD
北大核心
2021年第3期140-146,共7页
Journal of Arid Land Resources and Environment
基金
国家自然科学基金(51669031)资助。
关键词
颗粒流
冰碛土泥石流
起动过程
临界含水率
结构控制
particle flow
flow of moraine soil
starting process
critical water content
structure control
