基于裂离比的粗粒料级配曲线预测模型

FORECASTING MODEL OF GRAIN SIZE GRADING CURVES OF COARSE-GRAINED MATERIALS BASED ON DISCARDING RATIO

为了建立粗粒料在颗粒破碎下级配曲线的预测模型,将粗粒料的颗粒破碎划分为3个阶段,并在模型建立过程中引入裂离比Rk的概念。结合石英砂岩、片麻岩、砂板岩、角砾岩、砂砾岩的颗粒破碎试验资料,在进行等比级数简化假设的基础上,分析裂离比与围压、干密度、粒径间的关系表明：当粒径为10-60 mm且围压为0.0-1.6MPa时,对于不同的颗粒材料,3-Rk均呈现出线性化关系,且该关系存在一个斜率折点。当颗粒粒径小于10 mm时,对磨圆后砂砾岩的试验资料进行分析发现,3-Rk的关系在围压为0.0-1.2 MPa范围内趋于整体线性。综合考虑围压、母岩强度与原始级配对裂离比的影响,当颗粒粒径为10-60 mm时,对于同粒组下的片麻岩、砂板岩、弱风化石英砂岩,其裂离比的变化规律具有归一性。由此提出裂离比Rk的预测计算公式,并初步给出参数取值范围,使基于裂离比概念的粗粒料级配曲线预测成为可能。

To construct a forecasting model of grading curve of coarse-grained materials considering breakage,particle breakage is divided into three stages. And the new concept of discarding ratio Rk is introduced in the model-building process. By investigating the relationship of discarding ratio with confining pressure,dry density and particle size with the breakage test results of quartz sandstone,gneiss,mixture of sandstone and slate,breccias and sandy conglomerate,it is indicated that on the simplified hypothesis of geometric progressional distribution,there is a linear relationship,which has a slope turning point between Rk and σ3,for different granular materials when particle size and confining pressure vary in the ranges of 10–60 mm and 0.0–1.6 MPa,respectively. By exploring the particle breakage of well-rounded sandy conglomerate,it is found that 3-Rk relationship becomes linear globally while particle size is less than 10 mm and confining pressure ranges from 0.0 to 1.2 MPa. Considering the combined effect of confining pressure,strength of mother rock and original particle size,it is concluded that the variation of discarding ratio is unanimous for the breakage of gneiss,mixture of sandstone and slate,weak weathering quartz sandstone with the same grain group once particle size changes from 10 to 60 mm. Thus a prediction formula for estimating discarding ratio is presented,and the ranges of its parameters are given preliminarily,which makes possible the forecast of soil grain size grading curve of coarse-grained materials based on the concept of Rk.