滑坡碎屑流对透过性柔性网的冲击动力特征研究

Research on the Impact Dynamics Characteristics of Landslide Debris Flows on Permeable Flexible Barriers

摘要:

柔性网是防治滑坡碎屑流的重要拦挡结构，其透过性对碎屑流冲击动力学特征尚未得到充分关注。基于离散元法，在不同来流Froude数和网径尺寸条件下，开展了碎屑流对透过性环形柔性网的冲击试验，建立了一种新型冲击力估算模型。结果表明：（1） 随着网径尺寸和Froude数的增加，流动层颗粒从柔性网中通过的概率增加，死区稳定性降低，共同提升了柔性网的透过性；（2） 当来流Froude数小于4时，碎屑流冲爬高度和冲击力对网径比并不敏感；在Froude数大于4后，随着柔性网对前端碎屑流透过能力增强，峰值冲击力时刻流动层直接传递到柔性网上的动量和死区的堆积质量降低，降低了流动层的冲击动力和死区的堆积静力；（3） 提出的分析模型可用于分析和估算碎屑流作用在透过性柔性网上的峰值冲击力。研究结果为柔性网的网径尺寸优化和结构设计提供了理论参考。

Abstract:

Flexible barriers are important barrier structures for preventing and controlling landslide de bris flows, but its permeability's effect on the impact dynamics characteristics of debris flows has not been sufficiently studied. Based on the discrete element method (DEM), impact tests of debris flows on permeable annular flexible barriers were conducted under different inflow Froude numbers and mesh sizes. A novel model for impact force estimation was then established. The results showed that: (1) as the mesh size and Froude number in-creased, the probability of flow layer particles passing through the flexible barriers increased and the stability of the dead zone decreased, collectively enhanc ing the permeability of the flexible barriers. (2) When the inflow Froude number was less than 4, the debris flow climbing height and impact force were not sensitive to the mesh size ratio. However, when the Froude number exceeded 4, as the per-meability of the flexible barriers to the front-end debris flow enhanced, the momentum directly transferred from the flow layer to the flexible barriers and the accu mulated mass in the dead zone at the peak impact moment decreased, thereby reducing the hydro-dy namic impact force of the flow layer and the hydro-static impact force of accumulation in the dead zone. (3) The proposed analysis model could be used to analyze and estimate the peak impact force of debris flows on permeable flexible barriers. The research findings provide theo-retical guidance for mesh size optimization and structural design of the flexible barriers.