片状颗粒间液桥力变化规律的计算研究

研究颗粒间液桥力有助于揭示非饱和土持水特性的内在机理. 为探究片状颗粒间液桥力演化规律, 从细观尺度研究非饱和土的水力特性机理, 使用Surface Evolver软件在两平行的片状颗粒间构建出三维液桥模型, 分析了液桥拉伸过程中接触角、液桥体积、分离距离以及固液接触线钉扎效应等对液桥力变化规律的影响. 基于圆弧假定, 计算相应条件下液桥力以及接触半径的大小, 并与上述模拟结果进行对比分析. 结果表明: 片状颗粒间液桥力随液桥体积增大而递增, 随分离距离的增大而递减, 随固液接触角的增大先增后减或一直递减; 液桥体积一定时, 在钉扎状态下, 其液桥力随着分离距离的增大迅速递增达到峰值, 而后逐渐降低; Surface Evolver模拟与液桥界面环形近似的计算结果相对比, 当固液接触角较大时(θ = 60°和θ = 80°), 二者相对误差在6%以内, 而当固液接触角减小到30°及以下时, 相对误差随之增大, 且颗粒间分离距离越大, 相对误差越大. 

STUDY ON THE EVOLUTION OF LIQUID BRIDGE FORCE BETWEEN FLAKY PARTICLES

Studying the liquid bridging force between particles can help reveal the internal mechanism of the water-holding properties of unsaturated soils. In order to explore the evolution law of the liquid bridge force between flaky particles and study the hydraulic characteristics of unsaturated soils from a meso-scale scale, the Surface Evolver software was used to construct a three-dimensional liquid bridge model between two parallel flaky particles, and the tension of the liquid bridge was analyzed. The influence of contact angle, liquid bridge volume, separation distance and the pinning effect of the solid-liquid contact line on the law of the change of the liquid bridge force during the process. Based on the arc assumption, calculate the liquid bridge force and the size of the contact radius under the corresponding conditions, and compare and analyze the results with the above simulation results. The results show that the liquid bridge force between flake particles increases with the increase of the liquid bridge volume, decreases with the increase of the separation distance, and first increases and then decreases or decreases with the increase of the solid-liquid contact angle; when the liquid bridge volume is constant In the pinning state, the force first increases rapidly with the increase of the separation distance, reaches the peak value, and then gradually decreases; the Surface Evolver simulation is compared with the calculation result of the annular approximation of the liquid bridge interface, when the solid-liquid contact angle is large (θ = 60° and θ = 80°), the relative error of the two is within 6%, and when the solid-liquid contact angle is reduced to 30° and below, the relative error increases, and the particles The greater the separation distance, the greater the relative error.