不良级配粗粒土渗透变形的数值试验

针对单一粒径粗粒组和细粒组混合而成的不良级配粗粒土,采用计算流体力学与离散元耦合方法,考虑孔隙水与固体颗粒的相互作用,模拟了一定水力比降作用下的渗透变形过程,研究了细粒的运动规律,对比分析了初始细粒含量对渗透变形过程的影响。在水力比降作用下,土样中细颗粒运移会经历两个阶段,初期渗透压密,运动速度较低,之后随着渗透变形发展,渗流通道和运移通道逐步开敞,细颗粒运移速度加快。渗透变形发展过程中,土样出水口和入水口位置细粒含量降低、局部水力比降减小,而中部细粒含量增大、局部水力比降缓慢增加。当土样中初始细粒含量达到40%时,土样中部细粒含量会提高,并逐渐出现明显淤积层。土体渗透变形取决于整个渗径上的渗透稳定性,土料自身颗粒粒径几何关系确定的内部稳定性不能完全表征土体的渗透稳定性。

Numerical simulation of seepage deformation process in poorly-graded coarse soil

A CFD-DEM coupled method is applied for numerical simulation of seepage deformation process of poorly-graded coarse soil. The migration law of fine particles under the effect of seepage was studied and the influence of the initial fine particle content on the seepage deformation process was compared. The initial stage is seepage compression, and the migration speed of fine particles is relatively low. Then with the development of seepage deformation, the seepage channel gradually opens, and the migration of fine particles is accelerated. With the development of seepage deformation process,the fine particle content and local hydraulic gradient of soil samples near the outlet and inlet part decrease,while the fine particle content of the middle slowly increases. When the initial fine particle content reaches 40%,with the fine particle content in the middle of the soil sample increasing,silting layer gradually appears. The seepage deformation of soil depends on the seepage stability of the whole seepage paths, and the internal stability of soil materials can not completely determine the seepage stability of soil. Under the action of hydraulic gradient,the fine particle migration in soil samples will go through two stages.