In this work, we present experimental results that show the feasibility of measuring three-dimensional displacement in models of dry granular avalanches. For this purpose, we have used a technique that is capable to measure simultaneously the three involved mutually perpendicular components of displacement on the free surface of the granular flow. The approach comprises two simultaneously used optical techniques: fringe projection, FP, and digital image correlation, DIC; the first technique yields the out-of-plane component of displacement, and the second one, the two in-plane components. Combination of both techniques is achieved by color encoding, which consists in using different color illumination sources for the two optical techniques, in conjunction with a camera recording in RGB. The resulting combination is robust since the illumination sources are non-coherent between them, avoiding any optical interference. This contribution shows the potentiality of the method to analyze dynamic events, by presenting temporal full-field sequences of displacement of small-scale granular flows down an inclined plane, at camera speeds up to 2000 fps. These types of measurements are valuable for validation of physical and numerical models related with the analysis of the dynamic behavior of granular flows in the earth. Because these phenomena, which include rock avalanches, debris avalanches, debris flows, and pyroclastic density currents, are among the most dangerous natural hazards in mountainous and volcanic areas, the possibility to foresee their behavior in a more precise way is extremely important in order to elaborate more rigorous physical models and improve the predictive capacity of the simulation software.

中文翻译：

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基于条纹投影和数字图像相关的小尺度颗粒流动态三维位移分析

在这项工作中，我们展示了在干颗粒雪崩模型中测量三维位移的可行性的实验结果。为此，我们使用了一种技术，该技术能够同时测量颗粒流自由表面上三个相互垂直的位移分量。该方法包括两种同时使用的光学技术：条纹投影 FP 和数字图像相关 DIC；第一种技术产生位移的平面外分量，第二种方法产生两个平面内分量。两种技术的结合是通过颜​​色编码实现的，颜色编码包括对两种光学技术使用不同的颜色照明源，并结合相机以 RGB 进行记录。由此产生的组合是稳健的，因为它们之间的照明源是非相干的，避免了任何光学干扰。这一贡献显示了该方法分析动态事件的潜力，通过呈现小尺度颗粒流在倾斜平面上的时间全场位移序列，相机速度高达 2000 fps。这些类型的测量对于验证与地球中颗粒流动态行为分析相关的物理和数值模型很有价值。因为这些现象，包括岩崩、碎屑崩塌、碎屑流和火山碎屑密度流，是山区和火山地区最危险的自然灾害之一，