Abstract This study aims to investigate the effect of basal boundary conditions on the initiation and propagation of desiccation cracking along the vertical direction in thin clay layer using discrete element method (DEM). A two-dimensional discrete model was proposed considering shrinkage kinetics and property change during the drying process. Different basal boundary constraints were simulated by applying bond between the soil particles and the fixed base particles of difference sizes. The simulation results were compared with the laboratory experiments. The results showed that the model can reproduce the main trend of desiccation process. Larger base particles produced more cracks in the specimen. Both cracks initiated from the top surface and cracks initiated from the bottom soil-base interface were observed and discriminated in the simulation. The model revealed the development of bottom-initiated cracks and unpenetrated cracks beneath the surface that may be neglected in traditional cracking simulations. The study suggests that the different initiation position of cracks is associated with the change of force distribution inside the specimen. Moreover, the effects of different boundary properties (the geometrical roughness, the frictional coefficient and the bond strength), particle density change and evaporation gradient on model performance were investigated.

中文翻译：

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不同基础边界条件下薄黏土层干裂离散元建模

摘要 本研究旨在利用离散元法(DEM)研究基础边界条件对薄粘土层中干裂沿垂直方向的萌生和扩展的影响。考虑干燥过程中的收缩动力学和性能变化，提出了二维离散模型。通过在土颗粒和不同尺寸的固定基颗粒之间施加键来模拟不同的基边界约束。模拟结果与实验室实验进行了比较。结果表明，该模型能够再现干燥过程的主要趋势。较大的基础颗粒会在试样中产生更多的裂纹。在模拟中观察并区分了从顶部表面开始的裂缝和从底部土基界面开始的裂缝。该模型揭示了在传统开裂模拟中可能被忽略的底部裂纹和地表下未穿透裂纹的发展。研究表明，裂纹起始位置的不同与试样内部受力分布的变化有关。此外，研究了不同边界特性（几何粗糙度、摩擦系数和结合强度）、颗粒密度变化和蒸发梯度对模型性能的影响。