From the understanding of dynamics and processes of rapid granular flows and the granular-segregation mechanism in gravity-driven flow, we can clarify the particle-composition structure in the downstream areas of avalanches in geophysical contexts, such as landslides, rock falls, and snow-slab avalanches. Such dynamics also provide a basis for geophysical studies. This study experimentally investigates the dynamic behavior and segregation phenomena of a density-bidisperse, rapid, granular flow down a quasi-2D, rough, inclined rectangular chute. Particles with two density ratios are used to investigate the mechanism of density-induced segregation, and four chute-inclination angles are tested to examine the influence of driving forces. The dynamics of the mixture flow—which includes the flow-depth evolution, stream-wise and depth-wise velocity profiles, shear rate, and granular temperature in the upper high-shear band of the flow—are obtained from particle image velocimetry (PIV) measurements. The two-dimensional concentration distributions of the particles in the stream-wise direction are also obtained using 2D image processing to determine the segregation state. In the upstream region, the variation in the concentration of heavier particles is defined as the strength of the density-induced segregation state, S_d. Our results indicate that the mixture-flow parameter—particularly the shear rate and the granular temperature in the upper high-shear band—crucially influence the strength of particle segregation in granular avalanches. In the upstream region, a higher shear rate and a higher granular temperature in the upper high-velocity band result in a smaller drag force in the mixture flow, causing stronger density-induced particle segregation. These results well describe the entire processes of dense granular flows, from upstream initiation to the downstream steady state. Therefore, they reveal the structure of the mixed flow in the depth direction and are expected to explain various gravity-driven mixture granular flows.

通过对快速颗粒流动的动力学和过程的了解以及重力驱动流中的颗粒分离机制，我们可以弄清地球物理环境中雪崩下游区域的颗粒组成结构，例如滑坡，落石和降雪-平板雪崩。这种动力学也为地球物理研究提供了基础。这项研究实验性地研究了沿准二维，粗糙，倾斜的矩形斜槽的密度双分散，快速，颗粒状流动的动力学行为和偏析现象。使用具有两个密度比的粒子来研究密度诱导的偏析机理，并测试四个滑道倾斜角以检验驱动力的影响。混合物流动的动力学-包括流动深度演变，从颗粒图像测速（PIV）测量获得了流的高剪切带上的流向和深度速度分布，剪切速率和颗粒温度。还使用2D图像处理确定偏析状态来获得沿流向的颗粒的二维浓度分布。在上游区域，较重颗粒的浓度变化定义为密度引起的偏析状态的强度，小号_d。我们的结果表明，混合流参数（特别是上部高剪切带中的剪切速率和颗粒温度）对颗粒雪崩中颗粒偏析的强度至关重要。在上游区域，较高的高速带中较高的剪切速率和较高的颗粒温度导致混合物流中的牵引力较小，从而导致较强的密度诱导的颗粒偏析。这些结果很好地描述了从上游引发到下游稳态的致密颗粒流的整个过程。因此，他们揭示了深度方向上混合流的结构，并有望解释各种重力驱动的混合颗粒流。