Numerical investigation of mode failures in submerged granular columns
Numerical investigation of mode failures in submerged granular columns
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DOI：
10.1017/flo.2023.23
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发表时间：
2023-04
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影响因子：
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通讯作者：
E. P. Montellà;J. Chauchat;C. Bonamy;D. Weij;G. Keetels;T. Hsu
中科院分区：
文献类型：
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作者：
E. P. Montellà;J. Chauchat;C. Bonamy;D. Weij;G. Keetels;T. Hsu
摘要 在水下沙坡中，土壤经常因两种主要机制的组合而受到侵蚀：破裂，是指形成浊流的陡坡的后退破坏；以及瞬时滑动楔形，称为剪切破坏，也有助于塑造土壤沉积物的形态。尽管失效模式有多种，但在本文中，我们使用双流体方法研究颗粒柱的破裂和剪切失效。该数值模型首先应用于模拟不同初始体积分数的小规模颗粒柱塌陷（Rondon et al., Phys. Fluids, vol. 23, 2011, 073301），以研究初始条件在主流动力学中的作用。对于松散堆积的颗粒柱，多孔介质最初收缩，由此产生的正孔隙压力导致快速塌陷。而在最初的密堆积柱中，多孔介质膨胀并产生负孔隙压力，稳定颗粒柱，从而导致缓慢塌陷。所提出的数值方法在形态和超孔隙水压力方面与实验数据表现出良好的一致性。数值结果扩展到大规模应用（Weij，博士论文，2020，代尔夫特理工大学；Alhaddad 等人，J. Mar. Sci. Eng.，第 11 卷，2023，560），称为破坏过程。这种现象可能自然发生在海岸或河流的堤坝和堤坝上，但也可能是人类在疏浚作业过程中引发的。结果表明，两相流模型正确预测了与破裂过程相关的膨胀行为和随后的浊流。
Abstract In submerged sandy slopes, soil is frequently eroded as a combination of two main mechanisms: breaching, which refers to the retrogressive failure of a steep slope forming a turbidity current, and instantaneous sliding wedges, known as shear failure, that also contribute to shape the morphology of the soil deposit. Although there are several modes of failures, in this paper we investigate breaching and shear failures of granular columns using the two-fluid approach. The numerical model is first applied to simulate small-scale granular column collapses (Rondon et al., Phys. Fluids, vol. 23, 2011, 073301) with different initial volume fractions to study the role of the initial conditions in the main flow dynamics. For loosely packed granular columns, the porous medium initially contracts and the resulting positive pore pressure leads to a rapid collapse. Whereas in initially dense-packing columns, the porous medium dilates and negative pore pressure is generated stabilizing the granular column, which results in a slow collapse. The proposed numerical approach shows good agreement with the experimental data in terms of morphology and excess of pore pressure. Numerical results are extended to a large-scale application (Weij, doctoral dissertation, 2020, Delft University of Technology; Alhaddad et al., J. Mar. Sci. Eng., vol. 11, 2023, 560) known as the breaching process. This phenomenon may occur naturally at coasts or on dykes and levees in rivers but it can also be triggered by humans during dredging operations. The results indicate that the two-phase flow model correctly predicts the dilative behaviour and the subsequent turbidity currents associated with the breaching process.