Post-erosion mechanical responses of internally unstable gap-graded soil under drained torsional simple shear and triaxial compression
Post-erosion mechanical responses of internally unstable gap-graded soil under drained torsional simple shear and triaxial compression
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DOI：
10.1016/j.sandf.2022.101224
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发表时间：
2022-12
影响因子：
3.7
通讯作者：
S. Chitravel;M. Otsubo;M. Kuno;R. Kuwano
中科院分区：
文献类型：
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作者：
S. Chitravel;M. Otsubo;M. Kuno;R. Kuwano
内部侵蚀是对河堤和水坝等水工土结构的主要威胁。本文重点研究由于渗流而导致颗粒骨架中的细颗粒运动而引起的扩散和扩散现象。本研究研究了内侵蚀对循环扭转剪切下的动态响应以及三轴压缩和扭转简单剪切下的单调响应的影响。使用细粉含量为 20% 的间隙级配二氧化硅混合物，使用新型侵蚀空心圆柱扭剪装置在松散、中等和致密条件下进行了一系列实验。侵蚀试验结果表明，临界水力梯度和侵蚀速率取决于密度，随着渗流的继续，观察到从膨胀到扩散的转变。无论样品密度如何，侵蚀后沿样品高度的径向应变和颗粒尺寸分布的变化不再均匀。此外，动态剪切结果表明，内部侵蚀后小应变剪切模量增加，但初始阻尼比降低，这可能是由于游离细粉的去除所致。此外，发现侵蚀和非侵蚀样本的弹性阈应变和参考剪切应变值分别较高。最后，基于排水单调加载，三轴压缩下侵蚀后峰值应力比显着增加，而扭转简剪下侵蚀后峰值应力比取决于加载方向垂直于渗流方向时的相对密度。这些观察表明，水平层理面在向下侵蚀后变得更弱，而垂直层理面变得更强。
Internal erosion is a major threat to hydraulic earth structures, such as river levees and dams. This paper focuses on suffusion and suffosion phenomena which are caused by the movement of fine particles in the granular skeleton due to seepage flow. The present study investigates the impact of internal erosion on the dynamic response under cyclic torsional shear and monotonic responses under triaxial compression and torsional simple shear. A series of experiments, using a gap-graded silica mixture with a fines content of 20%, is performed under loose, medium, and dense conditions using a novel erosion hollow cylindrical torsional shear apparatus. The erosion test results indicate that the critical hydraulic gradient and the rate of erosion are density-dependent, where a transition from suffosion to suffusion is observed as the seepage continues. Regardless of the sample density, variations in the radial strain and particle size distribution, along the specimen height after erosion, are no longer uniform. Furthermore, the dynamic shearing results show that the small-strain shear modulus increases, but the initial damping ratio decreases after internal erosion, probably due to the removal of free fines. In addition, the elastic threshold strain and reference shear strain values are found to be higher for the eroded and non-eroded specimens, respectively. Finally, based on drained monotonic loading, the post-erosion peak stress ratio increases remarkably under triaxial compression, while that under torsional simple shear depends on the relative density where the direction of loading is normal to the direction of seepage. These observations indicate that the horizontal bedding plane becomes weaker, while the vertical one becomes stronger after downward erosion.