泥石流浆体黏度计算中最大体积分数的确定  

Determination of the Maximum Packing Fraction for Calculating Slurry Viscosity of Debris Flow

作　　者：杨红娟[1,2] 韦方强 胡凯衡[2] YANG Hongjuan;WEI Fangqiang;HU Kaiheng(Key Laboratory of Mountain Hazards and Earth Surface Process,Chinese Academy of Sciences,Chengdu 610041;Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,Chengdu 610041,China;Chongqing Institute of Green and Intelligent Technology,Chinese Academy of Sciences,Chongqing 400714,China)

机构地区：[1]中国科学院山地灾害与地表过程重点实验室,成都610041 [2]中国科学院水利部成都山地灾害与环境研究所,成都610041 [3]中国科学院重庆绿色智能技术研究院,重庆400714

出　　处：《山地学报》2018年第3期382-390,共9页Mountain Research

基　　金：国家自然科学基金项目(41201011)~~

摘　　要：泥石流浆体的黏度是泥石流运动模型中的重要参数。利用相对黏度-颗粒体积分数的计算方法得到浆体黏度需要最大体积分数这一关键参数。本文利用不同来源泥石流堆积物中的细颗粒部分配置浆体开展流变实验,研究最大体积分数的确定方法。首先利用Anton Paar MCR301流变仪的同心圆筒系统测量每个细颗粒土体在不同颗粒体积分数下的流变曲线,通过宾汉模型得到各样品的塑性黏度,进而计算其与同温度下清水的相对黏度。然后利用6个应用较为广泛的相对黏度-颗粒体积分数计算方法对实验数据进行拟合,对各方法拟合的最大体积分数进行比较,分析其与细颗粒土体的特征体积分数(随机疏松堆积体积分数、随机密实堆积体积分数、击实体积分数、沉积稳定体积分数)的关系。结果显示对于同一土体配置的浆体,不同计算方法拟合的最大体积分数有所不同,但是同一种方法得到的不同土体的最大体积分数与土体的击实体积分数存在显著的线性关系,据此建立了各计算方法中最大体积分数的经验计算式。此外还建立了浆体相对黏度与颗粒体积分数、击实体积分数之间的指数关系式,该式可用于估算中等浓度和高浓度浆体与清水的相对黏度。The slurry viscosity is an important parameter for the numerical simulation of debris flows. It is usually calculated by formulas which define the relationship between relative viscosity （ηr） and particle volume fraction （Ф）. However, the maximum packing fraction （Фm） is pre-requisite when using these formulas. It represents the solid fraction at which the relative viscosity approaches infinity. To study the method for determining the maximum packing fraction, fine particle samples （ ≤ 1 mm） collected at nine debris-flow gullies, most of which were located in the area affected by the Wenchuan Earthquake, were used to perform rheological tests. The median grain size of the geo-materials ranged from 0.011 to 0. 081 mm. Slurries with different solid concentrations were prepared for each type of sample. The shear stress-rotational speed curves were measured using the concentric cylinder system of an Anton Paar MCR301 rheometer, and they were further used to derive the plastic viscosity with the Bingham model. Then the relative viscosity was computed as the ratio of the plastic viscosity of the slunrry to the viscosity of water measured at a same temperature. Six widely used ηr -Фb formulas were finally utilized to derive Фm for each sample based on the associated experimental data. Values of Фm obtained from different formulas were examined. The relations between Фm and some characteristic solid fractions of the experimental samples, including random loose packing fraction, random close packing fraction, compaction fraction, and deposition fraction, were also analyzed. It revealed that different ηr -Фb formulas would give different Фm values for the same geo-material. However, a linear relationship was found between Фm, and the compaction fraction for a given ηr -Фb formula. Consequently, empirical relationships had been established to estimate the Фm, parameter in ηr -Фb formulas employed in the present study. Moreover, an exponential relationship was found between ηr and ηr -Фb

关 键 词：泥石流 浆体 黏度 最大体积分数 宾汉模型 

分 类 号：TV144[水利工程—水力学及河流动力学] P642.23[天文地球—工程地质学]