摘要
吸附水含量随温度的变化是研究黏性土温度效应的核心问题.本文基于核磁共振技术能同时探测土体水分含量与分布,结合毛细水与吸附水在土体中作用的不同吸力范围、冰点值及含量随温度变化的差异性,提出了一种能快速无损测试土体吸附水含量的方法,并通过此方法测得3种不同土质试样吸附水含量随干密度和温度的变化.实验结果表明:室温下,随着干密度的增加,试样中吸附水含量降低,这主要是因为干密度的增加导致了土颗粒间距变小,土颗粒表面的一些扩散双电层出现重叠;未冻土中,吸附水含量随温度的变化趋势同时受土质和温度范围的影响,黏粒含量为70%试样的吸附水含量随温度的升高而升高,而黏粒含量为50%和30%试样的吸附水变化分两个阶段,0°C以上,吸附水含量随着温度的升高而升高,0°C以下,试样中的吸附水含量随温度的升高而降低,且黏粒含量为50%试样变化趋势更明显,但整体上3个试样的吸附水含量随温度的变化很小;在冻融循环升温路径的?3.2°C以下,冻土中未冻水主要为吸附水,双对数坐标下吸附水含量Sw与温度(Tm?T)的比例系数k的范围为?0.867~?0.744,这与理论值?1/3存在较大差异,认为这主要是由试样孔径、土颗粒表面粗糙度和静电力等诸多复杂因素导致.
The variation of adsorbed water content is the core issue in study of temperature effect of clay. The water content and distribution in soil is detected by NMR technique, combined with the difference of suction, freezing point and variation with temperature of capillary and water, a fast, nondestructive method is developed which can be used to determine the adsorbed water content of the soil. The variation of adsorbed water content with temperature and dry density is determined by the method. The result indicates that at room temperature, the adsorbed water of samples decreases with the increasing dry density. This is mainly due to the reducing space of soil particles during the increase of dry density and the overlapping of electric double layer. For unfrozen soil, the adsorbed water content is affected by soil constitutes and temperature. The adsorbed water content of the sample with a clay fraction of 70% increases with increasing temperature. But for samples with clay fraction of 30% and 50%, adsorbed water content increases with increasing temperature above 0~C and decreases with the increasing temperature below 0~C and the trend is especially obvious for sample with a clay fraction of 50%. Overall, the adsorbed water of three samples changes few with the variation of temperature. In warm path during a freezing-thawing cycle, unfrozen water in frozen sample is adsorbed water below -3.2~C and linear scaling factor k between adsorbed water content （Sw） and temperature （TIn-T） changes between -0.867^-0.744 which has a big difference from the theoretical value （-1/3）. We think the difference is mainly caused by the roughness of pore size, roughness of soil particles, electric force and some other complex factors.
出处
《中国科学：技术科学》
EI
CSCD
北大核心
2014年第3期295-305,共11页
Scientia Sinica(Technologica)
基金
国家重点基础研究发展计划("973"计划):构筑物与冻土地基热
力耦合作用的动力学过程(批准号:2012CB026102)
国家自然科学基金(批准号:41102199
51239010)资助项目
关键词
核磁共振
吸附水
干密度
温度
NMR, adsorbed water, dry density, temperature
