反复冻融循环对黄土孔隙比及渗透性的影响

Influence of iterative freezing-thawing on void ratio and permeability coefficient of loess

在冻融循环过程中,周期性的冻结与融化持续改变着土体内部结构,使土的孔隙比与渗透性不可避免地发生相应的变化。以陕西杨凌地区Q3黄土为研究对象,在封闭系统下通过对不同初始条件的黄土进行多次反复冻融循环(最多冻融循环50次),研究了杨凌黄土孔隙比与渗透系数的变化规律。试验结果表明,封闭系统下反复冻融循环后土样孔隙比和渗透系数变化的情况与试样初始条件密切相关。试样初始含水率越高,冻融循环破坏作用越强,延续时间更长,试样需更长的循环周期达到动态稳定;冻融循环过程中,试样孔隙比与渗透系数随干密度的改变有不同的变化趋势;30次冻融循环后,试样的孔隙比与渗透性逐渐趋于稳定。

During iterative freezing-thawing cycle,the structure of loess changes,so are the void ratio and permeability.A series of iterative freezing-thawing tests under closed system were conducted to obtain the variation law of void ratio and permeability coefficient of loess in Yangling region.The times of freezing-thawing varied from 1 to 50.It is found that,the changes of void ratio and permeability coefficient are closely related to the initial conditions of the soil samples;when initial water content is growing,destructive effect of freezing-thawing gets stronger and duration gets longer,it would take more times of freezing-thawing cycles to get a dynamic stability;void ratio and permeability have different variation tendencies with the change of dry density in freezing-thawing cycles;the void ratio and permeability tend to be constant after 30 times freezing-thawing cycles.