The cyclic properties of geosynthetic soil interface are crucial for reinforced soil structures subject to seismic loading. To investigate the mechanical geogrid-sand interface behavior under cyclic shear conditions, a series of numerical simulation cyclic shear tests were conducted using the discrete element method. The results revealed with increasing of shear cycles, dense sand sample gradually shrunk, exhibiting obvious softening characteristics. The vertical displacement of the sample under simulated 10 cyclic shear increases by 0.27 mm, which is 0.41 mm lower than that under 1 cyclic shear. Meanwhile, obvious dilation was observed in the shear band. As the number of cyclic shear increases, the region where the particle rotation occurs does not change significantly, ranging from 75 mm to 125 mm. Higher sample density made it more difficult for particles at geogrid-sand interface to rotate. Under the same number of cycles, denser samples had narrower shear bands, smaller shear strain shifts, and larger shear stiffness. The sand size is 0.5 mm, and the particle displacement concentrated in the 3 mm shear zone. After the completion of cyclic shear, dense sand had little effect on the porosity of the unreinforced sand affected zone, and the porosity after cyclic cycle was close to the initial porosity.

中文翻译：

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DEM 对循环直剪作用下土工格栅-砂界面力学行为的研究


土工合成土界面的循环特性对于承受地震载荷的加筋土结构至关重要。为了研究循环剪切条件下的机械土工格栅-砂界面行为，采用离散元法进行了一系列数值模拟循环剪切试验。结果表明，随着剪切循环次数的增加，致密砂样逐渐收缩，表现出明显的软化特性。模拟 10 次循环剪切下试样的垂直位移增加了 0.27 mm，比 1 次循环剪切下降低了 0.41 mm。同时，在剪切带中观察到明显的膨胀。随着循环剪切次数的增加，粒子旋转发生的区域没有显着变化，范围从 75 mm 到 125 mm。较高的样品密度使土工格栅-沙界面处的颗粒更难旋转。在相同循环次数下，密度较大的样品具有较窄的剪切带、较小的剪切应变位移和较大的剪切刚度。沙子尺寸为 0.5 mm，颗粒位移集中在 3 mm 的剪切带。循环剪切完成后，致密砂对无筋砂影响带的孔隙度影响不大，循环循环后的孔隙度接近初始孔隙度。