为探究膨润土泥浆中粗颗粒粒径组成对浆液渗透行为的影响，基于DEM建立颗粒流数值模型，利用球形颗粒形成孔隙，以实际泥浆中的颗粒粒径分布为准，还原实际泥浆中粒径超过20 μm的粉粒和砂粒；以此前的室内渗透试验研究为基础，开展与之相对应的数值计算。计算结果显示： 1）泥浆中不同粗颗粒粒径组成对泥浆渗透堵塞过程有明显影响，随着泥浆中粗颗粒粒径逐渐增大，泥浆颗粒从渗透到堵塞形成，所消耗的泥浆颗粒质量呈现出先减小后增大的特点，证实了对于一个具体的孔隙介质，存在最佳堵塞粒径的结论； 2）向浆液中添加适量小于最佳粒径的连续级配粗颗粒，可以在泥浆渗透堵塞过程中获得最小的泥浆消耗量，数值模拟的试验结果与室内试验的研究结论一致； 3）在每一条颗粒渗透路径上，砂层的孔隙分布是随机的，颗粒的停滞深度是不同的，但同一直径的颗粒群的渗透深度有一定的规律性，颗粒越小，其分布的范围越大； 4）在实际工程中，建议采用0.2D15（累积质量达到15%时的地层颗粒粒径）作为最佳堵塞粒径，也可通过开展渗透试验确定具体地层的最佳堵塞粒径，将小于最佳堵塞粒径的砂颗粒均匀添加至膨润土基浆中，可以配制出同等条件下渗透滤失量较小的泥浆。
To investigate the influence of the particle size composition of coarse particles in bentonite slurry on the slurry penetration behavior, this paper built a particle flow numerical model based on dynamics and element modeling. By forming pores with spherical particles and using the actual particle size distribution in the slurry as the reference, the fine particles and sand particles with a diameter exceeding 20 μm in the actual slurry are simulated. Based on the previous penetration tests, corresponding numerical calculations are carried out. The simulation results show that: (1) The composition of different coarse particle diameters in the slurry has a significant impact on the process of penetration and clogging. As the diameter of the coarse particles in the slurry gradually increases, the mass of slurry particles consumed shows a trend of first decreasing and then increasing. This confirms the conclusion that for a specific pore medium, there exists an optimal diameter of coarse particles. (2) Adding an appropriate amount of continuous gradation coarse particles with diameters smaller than the optimal size to the slurry results in the minimum slurry consumption during the penetration. The simulation results are consistent with the research conclusions of the laboratory tests. (3) On each particle penetration path, the aperture is random, and the stagnation depth of the particles is different. For particles with same diameter, the penetration depth has a certain regularity. The smaller the particle, the wider the range of its distribution. (4) In practical, it is recommended to use 0.2D15 (particle size for which 15% by weight of particles in strata) as the optimal clogging particle size. Alternatively, this size can be determined through permeability tests. By uniformly adding sand particles smaller than the optimal clogging particle size to the bentonite-based slurry, a slurry with a lower permeability and fluid loss under the same conditions can be prepared.
