中颗粒粒径、级配对泥石流屈服应力的影响

Effect of medium-sized particle diameter and grading on yield stress of debris flow

摘要

【目的】一般情况下，泥石流屈服应力与固体体积浓度呈正相关，也会随着黏土黏性的增强而增大，同时还受粗颗粒特性的影响，而现有的室内流变试验中未将中颗粒性质对屈服应力的影响纳入考虑之中。为了研究中颗粒性质对屈服应力的影响，完善屈服应力计算模型，【方法】以泥石流体屈服应力为研究目标，选取4种不同目数的中颗粒石英砂作为研究对象，通过改变泥石流固体体积浓度、中颗粒粒径和级配，配制泥石流浆体进行室内流变试验，并对试验数据进行统计和分析。【结果】分析及对比结果显示：中颗粒级配越好，泥石流屈服应力就越小，反之，泥石流屈服应力就越大；当泥石流固体体积浓度C₀<0.47时，中颗粒粒径对泥石流屈服应力几乎无影响，当泥石流固体体积浓度C₀≥0.47时，中颗粒粒径与泥石流屈服应力呈负相关。【结论】试验结果表明：在粗颗粒研究基础上对中颗粒级配与中颗粒粒径进行修正后，得到了新的体积浓度修正系数，进一步完善了屈服应力的计算模型，并验证了其具有更好的科学性和可靠性。

Abstract

[Objective] Generally, the yield stress of debris flow is positively correlated with solid volume concentration and the enhancement of clay viscosity. It is also influenced by the properties of coarse particles as well. However, existing laboratory rheological experiments have not considered the influence of medium particle properties on yield stress. To investigate the influence of medium particle properties on yield stress and improve the yield stress calculation model, [Methods] the yield stress of debris flow was examined using four types of medium-particle quartz sand with different mesh sizes. By varying the solid volume concentration, medium particle size, and particle grading, debris flow slurry was prepared for laboratory rheological experiments, and the experimental data were statistically analyzed. [Results] Analysis and comparison result indicated that better medium particle grading result ed in lower yield stress, whereas poorer grading led to higher yield stress. When the solid volume concentration was C₀< 0.47, medium particle size had little effect on yield stress. When C₀≥0.47, medium particle size exhibited a negative correlation with yield stress. [Conclusion] The experimental result demonstrate that modifying medium particle grading and size, based on coarse particle studies, resulting a new volume concentration correction coefficient. This refinement further improves the yield stress calculation model, enhancing its scientific accuracy and reliability.

关键词

泥石流 / 屈服应力 / 粒径 / 级配 / 形状 / 影响因素

Key words

debris flow / yield stress / particle diameter / grading / shape / influence factors

基金资助

国家自然科学基金(U21A2032)