渗流侵蚀作用下土体压缩行为的演化特性

    Compression Behavior of the Soils Subjected to Seepage Erosion

    • 摘要: 土体在不断增大的水头差作用下会出现渗透侵蚀,并最终演变为渗透破坏,渗透破坏威胁堤防等土石建筑物安全。压缩性能是堤防值得关注的重要特性,掌握在不同渗透侵蚀作用后的压缩行为,对评估堤防稳定性具有重要意义。针对不稳定黏土和不稳定砂土,开展在不同水头(低于临界水力梯度)作用下渗透试验,进而开展对应侵蚀试样的压缩试验,探究土体受侵蚀程度对后期压缩行为的影响。结果表明:相比不稳定黏土,不稳定砂土的临界水力梯度更低,更易发生渗透破坏;经历不同渗透侵蚀程度的不稳定土,高应力状态下的e-lg p压缩曲线,均呈线性关系,且对应压缩指数λ差异不大。然而,最终正常固结线随侵蚀程度增加逐渐下移,表明渗透侵蚀显著改变了土体结构,侵蚀程度越高,土体越容易被压密,进而发生重力沉陷。可见,土体受侵蚀程度显著影响其后期压缩行为,掌握其规律对提前预测堤防渗透破坏具有显著价值。

       

      Abstract: Seepage erosion, driven by escalating hydraulic gradients within the soil matrix, leads to seepage-induced deterioration, posing a significant hazard to the structural integrity of embankments. The compression behavior of embankments is a crucial characteristic that requires attention. Understanding how this behavior evolves under various extents of seepage erosion is essential for evaluating embankment stability. Infiltration tests were conducted on an internally unstable clay and sand under water heads below the critical hydraulic gradient. Subsequent compression tests on the resultant eroded samples assessed how erosion extent influences subsequent compression behavior. The results indicate that internally unstable sand exhibits a reduced critical hydraulic gradient and increased susceptibility to seepage-induced damage compared to internally unstable clay. Compression curves for internally unstable soils subjected to different extents of seepage erosion follow linear trends under high-stress conditions, with negligible variation in associated compression indices (λ). However, the normal consolidation lines (NCL) for soils subject to varying extents of seepage erosion do not align; instead, they progressively shift downward as erosion intensifies. This indicates that seepage erosion profoundly alters soil structure, rendering soils more susceptible to compression and subsequent gravitational settlement as the extent of erosion increases. Understanding the relationship between soil erosion and subsequent compression behavior is crucial for predicting embankment seepage failure in advance.

       

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