Rheological properties of clayey soils originating from flow-like landslides
Rheological properties of clayey soils originating from flow-like landslides
复制标题
源自流状滑坡的粘土的流变特性
作者：
S. Carrière;D. Jongmans;G. Chambon;G. Bièvre;B. Lanson;L. Bertello;M. Berti;M. Jaboyedoff;J. Malet;J. Chambers
粘性土壤中的流动状滑坡对人口和基础设施构成严重威胁，在过去十年中一直是许多研究的主题。然而，尽管随着城市化的发展，对滑坡缓解的需求越来越大，但对固体-流体转变中涉及的瞬态机制仍然知之甚少。表征固体-流体转变的一种方法是对粘性土样品进行流变测试，以评估粘度随剪切应力的演变。在这项研究中，我们进行了土工和流变测试的粘土样品从六个流动样滑坡，以评估这些粘土表现出类似的特性时，他们的流动（固体-流体转换）。结果表明：（1）除一种土外，其它土均表现出屈服-应力流体特性，且粘性存在分叉（2）粘度分叉的幅度越大，相应的剪切模量G下降越大;含水量（w）与液限（LL）的偏差似乎是控制这些土在固-流转变时共同力学行为的关键参数。我们提出了描述临界剪切应力τc、临界剪切速率γc和剪切模量G随偏差w-LL变化的指数规律。
Flow-like landslides in clayey soils represent serious threats for populations and infrastructures and have been the subject of numerous studies in the past decade. However, despite the rising need for landslide mitigation with growing urbanization, the transient mechanisms involved in the solid-fluid transition are still poorly understood. One way of characterizing the solid-fluid transition is to carry out rheometrical tests on clayey soil samples to assess the evolution of viscosity with the shear stress. In this study, we carried out geotechnical and rheometrical tests on clayey samples collected from six flow-like landslides in order to assess if these clayey soils exhibit similar characteristics when they fluidize (solid-fluid transition). The results show that (1) all tested soils except one exhibit a yield-stress fluid behavior that can be associated with a bifurcation in viscosity (described by the critical shear rate γċ$$ dot{gamma_c} $$) and in shear modulus G; (2) the larger the amplitude of the viscosity bifurcation, the larger the associated drop in G; and (3) the water content (w) deviation from the Atterberg liquid limit (LL) seem a key parameter controlling a common mechanical behavior of these soils at the solid-fluid transition. We propose exponential laws describing the evolution of the critical shear stress τc, the critical shear rate γċ$$ dot{gamma_c} $$, and the shear modulus G as a function of the deviation w-LL.