泥石流中颗粒相摩擦应力影响特性研究

Debris Flow with Varying Frictional Portions for Coarse Particles

泥石流固体物质组成及流动现象具有多样性,需要根据具体情况选择合适的模型进行描述。本文主要针对固体和物质组成较粗、细颗粒泥沙较少的泥石流运动特性进行探讨。鉴于在颗粒间相互作用应力的确定方面,弥散应力和碰撞应力都相对容易确定,而颗粒间直接持续接触时产生的表面摩擦应力往往不易确定,本文提出了一个简单方法代替通常采用的经验公式法,据此分析了不同条件下摩擦应力对泥石流总应力的贡献,及其对泥石流运动特性的影响,给出了层移质与水石流形成与转化的判别条件,文中的分析结果对理解层移质与水石流运动机理十分有益。

Debris flow is noted for its complex material compositions, unusual flow patterns and potential ability to induce serious disasters. Among the different types of debris flows, the water-rock flow is typical and thus has been studied widely around the world. For this kind of specific flow, the total stress is composed of three parts, i.e., the frictional stress, the dispersive stress and the collisional stress. Since the last two parts can be reasonably modeled and the first part is still lack of satisfactory understandings, the determination of the frictional constitutive relation becomes the key to the insight into the mechnism of debris flow. In the present paper, a simple way is introduced by assuming that the frictional stress is part of the total stress for the particles, and the behaviours of debris flow are fully studied by use of varying proportional coefficients reflecting the frictional share in the total ranged between zero and one. In addition, the criterion and differences between the laminated flow and the water-rock flow are also discussed. As indicated in the paper, most of the special characteristics in water-rock debris flows are related to frictional stress. So far, the knowlege to the frictional constitutive relationis is far not enough for us to do quantitative study since each existing relation often include several empirical parameters to be determined and give quite differnt results with varying magnitude orders. In such cases, the present study is particularly useful for the deeper understanding of the effect of frictional stress on debris flows.