ISSN 1000-3665 CN 11-2202/P

    基于斜槽试验的颗粒流动力学特性研究

    The mechanical characteristics of granular flow based on the chute experiment

    • 摘要: 碎屑岩崩事件属于颗粒流运动,动力学特性复杂,但目前对其了解较为匮乏,阻碍了有效防治进程。文章以圆溪砂作为试验颗粒开展斜槽试验,通过变化倾斜角度(θ)与闸门开口高度(hg),综合探究颗粒流运动特征。结果显示:(1)不同流动厚度阶段的颗粒流中,其弗劳德数与无量纲厚度较好地服从线性增大关系。(2)恒定的闸门开口高度下,厚度稳定阶段的切向力Fy与法向力Fz均随倾角的增大而减小;恒定的倾角下,FyFz则随开口高度的降低而减小,并且各工况厚度稳定阶段的基底摩擦系数( \mathit\mu _\mathbfb) 随厚度减小整体呈减小趋势。(3)颗粒流的侧面速度(v)分布曲线在厚度较大时总体呈凸凹型分布,为颗粒流非局部流变模型提供了清晰的试验证据。通过参数tan4(θ)可以将速度分布曲线较好地重合在一条凸凹型主线上。此外,单次颗粒流动中越接近表面位置的颗粒动能温度越大。研究结果能够为滑坡、岩崩等地质灾害的预测与预防提供科学参考。

       

      Abstract: Clastic rock avalanches are typically classified as granular flows and are characterized by complex dynamic behaviors. However, current understanding of these processes remains limited, hindering the development and implementation of effective hazard prevention and mitigation strategies. To comprehensively investigate the dynamic characteristics of granular flow, this study utilized rounded sand as the experimental material and conducted chute experiment by varying the inclination angle θ and the gate size hg. The results indicate that at various stages of a single granular flow event, the dimensionless velocity presents a linear relationship with flow thickness, consistent with previously established flow rules. For a constant gate size hg, both the tangential force (Fy) and normal force (Fz) decrease with growing slope during the stable thickness phase; At a fixed slope θ, the values of Fy and Fz diminish as the gate size drops. Additionally, the basal friction coefficient \mu _\mathrmb , which is defined as Fy/Fz, generally exhibits a descending trend as the flow thickness decreases during the stable thickness phase across different conditions. When the flow thickness h is large, the velocity profiles tend to display a convex-concave distribution, providing empirical support for the non-local rheological behavior of granular flows. By rescaling the dimensionless velocity using tan4(θ), all velocity distribution curves can be effectively collapsed onto a single convex-concave master curve. During a single granular flow event, the closer the particles are to the surface, the higher their kinetic temperature T would be. The findings of this study can provide theoretical support for the prediction and prevention of geological disasters such as landslides, rock avalanches, and debris flows.

       

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