冻融循环作用下黄土孔隙率变化规律  

The changing rule of loess' s porosity under freezing-thawing cycles

作　　者：肖东辉[1,2] 冯文杰[1] 张泽[1] 

机构地区：[1]中国科学院寒区旱区环境与工程研究所冻土工程国家重点实验室,甘肃兰州730000 [2]中国科学院大学,北京100049

出　　处：《冰川冻土》2014年第4期907-912,共6页Journal of Glaciology and Geocryology

基　　金：国家自然科学基金项目(41023003;41301070);中国科学院"西部之光"博士项目;教育部留学回国人员科研启动基金项目(第46批)资助

摘　　要：冻融循环作用通过破坏黄土颗粒的大小和土体的骨架及组构影响黄土的孔隙率.通过颗粒分析实验发现冻融循环后土体颗粒有变小趋势,且集中分布在0.01-0.05 mm,在冻融10次后颗粒大小趋于稳定.对经历冻融循环后的黄土进行压汞实验,发现随着冻融次数的增加,土体孔隙中的大孔径先减少,后增多;小孔径先增多,后减少,最后向5-10μm范围内集中.土的孔隙率也随冻融次数的增加而发生变化.原状黄土的孔隙率在冻融5次时达到最小值,在冻融10次时达到最大值,冻融10次之后原状黄土的孔隙率在40%上下波动,达到稳定状态.重塑黄土在冻融3次时孔隙率减少了6%并达到最小值,在冻融5次时孔隙率增加3%并达到最大值,最后在40%上下波动,达到稳定状态.渗透系数的变化曲线与通过压汞实验获得的孔隙率变化曲线相似,印证了随着冻融次数的增加黄土的孔隙率呈先减小,后增大,然后趋于稳定的变化规律.In seasonal frozen regions, as the internal structures of soil changes periodically under freezing-tha- wing cycles, the soil pore and skeleton will change inevitably. Through particle analysis, it is found that soil particles tend to be smaller and concentrate in the range of 0.01 - 0.05 mm after freezing-thawing cycles, and the particle size tends to be stationary after tenth freezing-thawing cycles. Mercury injection experiment was carried on the loess after freezing-thawing cycles, which demonstrates that the large aperture of soil decreases first, and then increases with freezing-thawing cycles increasing; while the condition is contrary to the small aperture of soil. At last, concentrating on the range of 5 --10 μm. In this experiment, the porosity changes with freezing- thawing cycles. Comparing with unfrozen loess, the porosity of intact loess decreases about 9% after five freez- ing-thawing cycles and reaches to the minimum; it increases about 1.5 % and reaches to the maximum after ten freezing-thawing cycles. After ten freezing-thawing cycles, the porosity of intact loess fluctuates at 40% and reaches to steady state. The remolded loess decreases about 6% relatively and reaches to the minimum after three freezing-thawing cycles; it increases about 3 % and reaches the maximum after five freezing-thawing cycles. Af- ter five freezing-thawing cycles, the porosity of remolded loess fluctuates around 40% and reaches to steady state. With freezing-thawing cycles increasing, the porosity of intact loess fluctuates between 32.5 % and 42.6% while the remolded loess fluctuates between 34.8% and 43.3%. The changing range of intact loess＇s porosity is greater than that of remolded one. The changing curves of the permeability coefficient are similar with the porosi- ty which obtains from the mercury injection experiment. It also verifies the changing law of porosity.

关 键 词：冻融循环 颗粒分析 黄土 孔隙率 

分 类 号：P642.14[天文地球—工程地质学]