The rheological behavior of natural slurries consisting of fine-grained, reconstituted debris-flow deposits on pyroclastic terrains having different solid concentrations (ranging from 30 to 42%) has been investigated using a rotational rheometer equipped with a vane rotor system. Experiments were done by increasing the applied shear stress step by step; then a decreasing stress ramp was applied following the same shear stress levels. The slurry mixtures exhibit a typical yield-stress fluid behavior with a static yield stress larger than the dynamic yield stress. In the range of the shear rate corresponding to the flow-like behavior the slurry mixtures behave as a dilatant fluid at lower grain concentrations and as a pseudoplastic fluid in correspondence with the higher grain content, showing a strong discrepancy from the Bingham idealization. The rheological behavior is better interpreted by a Herschel-Bulkley model, whose rheological parameters strongly depend on the granular concentration. Therefore, a generalized Herschel-Bulkley model accounting for the bulk sediment concentration effect is proposed.

使用装有叶片转子系统的旋转流变仪，研究了在固体含量不同（范围为30％到42％）的火碎屑地形上由细颗粒，重构的泥石流沉积物组成的天然浆料的流变行为。通过逐步增加所施加的剪切应力来进行实验。然后按照相同的剪应力水平施加减小的应力斜率。浆料混合物表现出典型的屈服应力流体行为，其静态屈服应力大于动态屈服应力。在对应于类似流的行为的剪切速率的范围内，浆液混合物在较低的晶粒浓度下表现为膨胀流体，而在较高的晶粒含量下表现为假塑性流体，与宾汉姆理想化有很大的差异。流变行为可以通过Herschel-Bulkley模型更好地解释，该模型的流变参数很大程度上取决于颗粒浓度。因此，提出了一种考虑了大量沉积物浓度效应的广义Herschel-Bulkley模型。