摘要
为研究不同温度模式下土体冻结特性,利用冻结试验装置对长春地区粉质黏土进行单向冻结试验。通过改变试验装置顶板温度及温度变化速率,研究分析试验过程中土体温度变化,试验前后土体含水率变化,试验后试样冷生构造、竖向冻胀位移。试验结果表明,土体温度变化大致分为四个阶段:骤降,回升或缓降,持续降温,恒定。相同降温速率,顶底板温度梯度越大,第二阶段温度回升程度越大;顶底板温度梯度相同时,降温速率越大,第二阶段温度回升程度越小。试验结束后,土体外表面出现网状裂缝且沿深度方向裂缝变宽,网状构造宽度与温度梯度大小成正比;土体内部有明显水分结晶,连续分凝冰包裹土体形成类似蜂窝状结构,其中存在一定肉眼可见的未冻水,且降温速率越小,肉眼可见未冻水含量越少。靠近控温顶板(冷端)土体含水率显著增加,靠近控温底板(暖端)土体含水率减小或基本不变,降温速率相同,温度梯度越大,冷端附近土体含水量增加越明显,相同冻结温度下,降温速率越低,冷端附近含水量增量越大。土体竖向冻胀量与温度梯度成正比,降温时间30 min条件下,冷端温度由0℃降低至-15℃冻胀量增加趋势较大,降温时间为60 min时,-10~-15℃温度变化区间冻胀量变化趋势最大。
In order to study the freezing characteristics of soil under different temperature modes,the unidirectional freezing test of silty clay in Changchun area was carried out by using the freezing test device.By changing the temperature and temperature change rate of the roof of the test device,the temperature change of the soil during the test,the water content change of the soil before and after the test,the cold structure and vertical frost heave displacement of the sample after the test were studied and analyzed.The test results show that the soil temperature change is roughly divided into four stages:sudden drop,rebound or slow drop,continuous cooling,constant.At the same cooling rate,the greater the temperature gradient of the roof and floor,the greater the temperature recovery in the second stage;When the temperature gradient of the roof and floor is the same,the greater the cooling rate,the smaller the temperature recovery in the second stage.After the test,reticular cracks appeared on the outer surface of the soil and widened along the depth direction.The width of the reticular structure was proportional to the temperature gradient.There is obvious water crystallization inside the soil,and the continuous segregated ice wraps the soil to form a honeycomb-like structure,in which there is a certain amount of unfrozen water visible to the naked eye,and the smaller the cooling rate,the less the unfrozen water content visible to the naked eye.The water content of the soil near the temperature control roof(cold end) increases significantly,and the water content of the soil near the temperature control floor(warm end) decreases or remains basically unchanged,and the cooling rate is the same,The greater the temperature gradient,the more obvious the increase of soil moisture content near the cold end.At the same freezing temperature,the lower the cooling rate,the greater the water content increment near the cold end.The vertical frost heave of the soil is proportional to the temperature gradient.Under the condition of
作者
孙超
王培金
郭浩天
宋韬
王寒冬
SUN Chao;WANG Peijin;GUO Haotian;SONG Tao;WANG Handong(College of Surveying,Mapping and Exploration Engineering,Jilin Jianzhu University,Changchun 130118,China;Institute of Geotechnical Engineering in Seasonal Frozen Region,Jilin Jianzhu University,Changchun 130118,China;Jiangsu Institute of Hydrogeological and Engineering Geological Survey,Huai’an 223001,Jiangsu,China)
出处
《冰川冻土》
CSCD
2024年第6期1839-1848,共10页
Journal of Glaciology and Geocryology
基金
第七届中国科协青年人才托举工程(2021QNRC001)
吉林省科技发展计划项目(YDZJ202201ZYTS490)资助。
关键词
单向冻结
降温速率
水分迁移
冻结特性
冷生结构
unidirectional freezing
cooling rate
moisture migration
freezing characteristics
cold-formed structure
