Natural alluvial foundations are inherently heterogeneous. To enhance seepage safety, a cut-off wall is commonly embedded in a dam foundation. However, walls can also have stochastic defects. The dual uncertainties arising from soil heterogeneity and wall defects pose significant challenges for seepage safety evaluation. In this study, systematic numerical simulations were conducted on an internally unstable dam foundation based on a four-constituent mixture framework. Soil heterogeneity was characterized by stochastic initial hydraulic conductivity and initial fines content. An erosion model, specifically incorporating the influence of overburden pressure, was employed to quantify suffusion. A probabilistic assessment utilizing Monte Carlo simulations revealed that suffusion in heterogeneous fields could be more severe than that in homogeneous fields. Various combinations of stochastic soil properties and defect locations can result in substantial disparities in seepage and erosion fields. The mean values of the total flux and the fines eroded ratio are insensitive to the spatial variation length, while their deviations increase with increasing spatial variation length, leading to larger uncertainties in the leakage channel morphology. For highly heterogeneous alluvial foundations with large spatial variations, conventional seepage and suffusion analyses that rely on homogeneous assumptions may considerably underestimate the internal erosion risk.

中文翻译：

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具有随机缺陷截断壁的非均质坝基的灌注特性


天然冲积地基本质上是异质的。为了提高渗流安全性，通常在水坝基础中嵌入截流墙。但是，墙壁也可能具有随机缺陷。土体异质性和壁面缺陷带来的双重不确定性对渗流安全性评价提出了重大挑战。本研究基于四组分混合物框架，对内部不稳定的大坝基础进行了系统的数值模拟。土壤非均质性以随机初始导水率和初始细粒含量为特征。采用侵蚀模型，特别是结合覆盖层压力的影响，来量化溶出。利用蒙特卡洛模拟的概率评估表明，非均质场中的浸润可能比均质场中的浸润更严重。随机土壤特性和缺陷位置的各种组合可能导致渗流和侵蚀场的巨大差异。总磁通量和细粉侵蚀比的平均值对空间变化长度不敏感，而它们的偏差随着空间变化长度的增加而增加，导致泄漏通道形态的不确定性更大。对于空间变化较大的高度非均质冲积地基，依赖于均质假设的常规渗流和渗流分析可能会大大低估内部侵蚀风险。