Sensitivity of Clay Suspension Rheological Properties to pH, Temperature, Salinity, and Smectite-Quartz Ratio
Sensitivity of Clay Suspension Rheological Properties to pH, Temperature, Salinity, and Smectite-Quartz Ratio
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DOI：
10.1002/2017gl075334
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发表时间：
2017-10-16
影响因子：
5.2
通讯作者：
Morisaki, Tomonori
中科院分区：
文献类型：
--
作者：
Kameda, Jun;Morisaki, Tomonori
了解粘土悬浮液的流变特性对于评估泥石流或浑浊流等沉积物重力流的行为至关重要。我们在温度为7℃，盐浓度为0.6M的条件下对蒙脱石-石英复合悬浮液进行了流变学测量。这代表了海底条件下含蒙脱石的沉积物。用宾汉流体模型对得到的流动曲线进行了拟合，确定了各悬浮液的宾汉屈服应力和动态粘度。在蒙脱石-石英混合比不变的情况下，随着悬浮液固水比的增大，其屈服应力和动态粘度有增大的趋势。在固水比不变的情况下，这些值随蒙脱石-石英混合物中蒙脱石含量的增加而增加。探索不同物理化学条件(PH1.0-9.0；温度2-30摄氏度；电解液(氯化钠)浓度0.2-0.6M)的附加实验表明，温度的影响可以忽略不计，而pH对悬浮液的流变性有适度的影响。更重要的是，电解液浓度对流动行为有很大的影响。这些变化可以通过蒙脱石-蒙皂石颗粒之间以及悬浮液中蒙皂石-石英颗粒之间的直接和/或间接(双层)相互作用来解释。尽管蒙皂石被认为是一种摩擦较弱的材料，但我们的实验结果表明，它的出现可以降低斜坡破坏开始的可能性。此外，蒙脱石还能有效地抑制边坡失稳后的扩展距离。
Understanding the rheological properties of clay suspensions is critical to assessing the behavior of sediment gravity flows such as debris flow or turbidity current. We conducted rheological measurements of composite smectite-quartz suspensions at a temperature of 7 degrees C and a salt concentration of 0.6M. This is representative of smectite-bearing sediments under conditions on the seafloor. The flow curves obtained were fitted by the Bingham fluid model, from which we determined the Bingham yield stress and dynamic viscosity of each suspension. At a constant smectite-quartz mixing ratio, the yield stress and the dynamic viscosity tend to increase as the solid/water ratio of the suspension is increased. In the case of a constant solid/water ratio, these values increase with increasing smectite content in the smectite-quartz mixture. Additional experiments exploring differing physicochemical conditions (pH1.0-9.0; temperature 2-30 degrees C; and electrolyte (NaCl) concentration 0.2-0.6M) revealed that the influence of temperature is negligible, while pH moderately affects the rheology of the suspension. More significantly, the electrolyte concentration greatly affects the flow behavior. These variations can be explained by direct and/or indirect (double-layer) interactions between smectite-smectite particles as well as between smectite-quartz particles in the suspension. Although smectite is known as a frictionally weak material, our experimental results suggest that its occurrence can reduce the likelihood that slope failure initiates. Furthermore, smectite can effectively suppress the spreading distance once the slope has failed.