冻融循环作用下土体冻结锋面移动规律试验研究  

Experimental study of the freezing front movement owing to freezing-thawing cycles

作　　者：张宇[1,2] 李东庆[1] 明锋[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》2016年第3期679-684,共6页Journal of Glaciology and Geocryology

基　　金：国家重点基础研究发展计划项目(2012CB026102);国家自然科学基金项目(41271080);冻土工程国家重点实验室项目(SKLFSE-ZQ-35);中国科学院西部行动计划项目(KZCX2-XB3-19)资助

摘　　要：冻融循环作用改变了土体结构及热物理性质,进而影响了土体温度变化过程,土体冻结锋面的稳定位置也随之变化.为研究冻融循环作用下土体冻结锋面的移动规律,进行了开放系统下的兰州黄土冻融循环试验.试验结果表明:冻结初期冻结锋面迅速下移,冷端温度稳定后其下移速度降低,当土体温度达到平衡时,冻结锋面位置趋于稳定;冻结锋面稳定深度随冻融循环次数的增加而增加.为阐述黄土冻结锋面随着时间变化规律,采用时间比拟法得到了冻融循环次数与冻融时间相似比拟曲线.由拟合曲线得第6次冻融循环后土体冻结锋面稳定在土样高度24.4 mm处,实测稳定在24.3 mm处,相对误差为0.4%.Freezing- thawing cycles result in changes of the structure and thermal physical properties of soil,which affect the process of soil temperature change,leading to the shift of stable position of soil freezing front.In order to study the freezing front movement process under the effect of freezing- thawing cycles,a series of freezing-thawing experiments on Lanzhou Loess under an open system were conducted. It is found that freezing front moves rapidly from top to bottom during the early period of soil freezing,while the speed reduces when the cold end temperature reaches a stable state. When soil temperature field reaches a stable state,the freezing front position tends to be stationary. The freezing front stability depth increases with freezing- thawing cycles. To expound the freezing front movement regularity with time,an analogy curve is adopted by using analogy method,which transforms the freeze-thawing cycles to time. After six freezing-thawing cycles the freezing front position is at the height of 24.4 mm,derived from the fitting curve,while the measured position is at the height of 24.3mm,with a relative error of 0.4%.

关 键 词：黄土 冻结锋面 冻融循环 试验研究 比拟法 

分 类 号：P642.14[天文地球—工程地质学]