Yield stress materials have a wide range of commercial applications. Yet, the suitable way of determining the yield stress values of a given material has been the subject of many studies and debates. Yield stresses are dependent on the material (shear) history and composition, which implies that robust protocols should be developed to study the yield stress dependence on a given parameter. In this study, three natural mud samples from a port having different densities were chosen for analysis. Four different geometries including concentric cylinders (Couette), cone and plate, parallel plates, and vane geometries were used. Our aim was to find the geometry and measurement protocol that best adapted to natural mud samples: the measurement should be reasonably fast and the major changes in sample structure (two-step yielding) should be recorded within the same measurement. Various rheological experiments such as stress sweep, oscillatory amplitude sweep, creep and stress growth tests were tested. Two-step yielding behavior was observed for the mud samples in stress sweep and amplitude sweep tests. The first yield point was linked with the breakage of interconnected network of aggregates/flocs while the second one was attributed to the collapse of aggregates into the smaller flocs or individual particles. Stress sweep tests proved to be practical, time efficient, and reliable tests for measuring yield stress values. Our study showed that Couette and parallel plate geometries are the most suitable geometries for analyzing the two yield stresses of the samples. Vane geometry is appropriate to study consolidated (solid-like) systems as for these samples a Couette geometry cannot be used because the bob could get stuck during the experiment.

屈服应力材料具有广泛的商业应用。然而，确定给定材料的屈服应力值的合适方法一直是许多研究和辩论的主题。屈服应力取决于材料（剪切）的历史和成分，这意味着应该制定鲁棒的协议来研究给定参数对屈服应力的依赖性。在这项研究中，选择了来自密度不同的港口的三个天然泥浆样本进行分析。使用了四种不同的几何形状，包括同心圆柱（Couette），圆锥和板，平行板和叶片几何。我们的目标是找到最适合天然泥浆样品的几何形状和测量方案：测量应相当快，并且样品结构的主要变化（两步屈服）应记录在同一测量中。测试了各种流变学实验，例如应力扫描，振荡幅度扫描，蠕变和应力增长测试。在应力扫描和振幅扫描测试中，观察到了泥浆样品的两步屈服行为。第一个屈服点与聚集体/絮凝体的互连网络的破坏有关，而第二个屈服点则归因于聚集体崩解成较小的絮状物或单个颗粒。应力扫描测试被证明是用于测量屈服应力值的实用，省时和可靠的测试。我们的研究表明，库埃特（Couette）和平行板几何形状是最适合分析样品的两个屈服应力的几何形状。