缩尺方法对粗粒料密度和渗透性影响的试验研究

依据规范推荐的粗粒料超径处理方法,对最大颗粒粒径为200 mm的宽级配料进行缩尺,控制最大颗粒粒径分别为60,20 mm,获取多条模拟级配,对原始级配、模拟级配粗粒料进行最大干密度试验和渗透试验,以研究不同缩尺方法、不同最大颗粒粒径条件下,粗粒料密度和渗透性的变化规律。结果表明:对于最大干密度试验,采用同种缩尺方法获取的最大干密度随最大颗粒粒径的减小而减小,表明粗颗粒的骨架作用显著。因缩尺后的P5含量使细颗粒处于较好的填充状态,可获得较高的最大干密度,其模拟级配试验值更接近原始级配,在此原则下相似级配法和混合法优于剔除法和等量替代法。对于渗透性试验,采用同种缩尺方法处理的最大颗粒粒径较小的试样,其渗透性也较小。细粒料土(尤其是粒径小于5 mm)的含量对渗透系数起到控制作用,缩尺处理应以尽量不改变较细粒料土的含量为原则。此原则下等量替代法最适用。

Experimental study on effects of different scaling methods on maximum dry density and permeability of coarse-grained materials

Scaling methods in Chinese codes and specifications were used to treat the wide-graded coarse-grained materials with maximum diameter of 200 mm. By controlling maximum particles to 60mm and 20mm respectively, several simulated grada-tions are obtained. And aiming to the simulated gradation and original gradation, the maximum dry density test and permeability test were conducted to the treated materials to study the effects of different scaling methods and maximum particles on the density and permeability of coarse-grained materials. Experimental results show that, for the maximum dry density test, the maximum dry density decreases with the maximum diameter by using the same scaling method, which demonstrates that coarse particles have a significant skeleton effect. Due to a proper P5 content after treatment, the fine particles achieve a better filling state and a maximum dry density could be obtained, the test value of simulated gradation is closer to that of original gradation. Under this principle, the similar gradation method and mixing method are superior to exclusion method and equivalent replacing method. For the permeability test, the permeability of material with relatively little maximum diameter is smaller by using the same scaling method. The content of fine particles significantly influences the permeability, especially the particles less than 5 mm. Under this principle, the equivalent replacing method is the most suitable.