兰州地区黄土冻胀特性和水平冻胀力试验研究  

Experimental Study on Frost-heaving Characteristics and Horizontal Frost-heaving Force of Loess in Lanzhou Area

作　　者：张正 马学宁[1] Zhang Zheng;Ma Xuening(College of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,P.R.China;Gansu Province Transportation planning,surver&Designing Institute Co.,Ltd.,Lanzhou)

机构地区：[1]兰州交通大学土木工程学院,兰州730070 [2]甘肃省交通规划勘察设计股份有限公司,兰州730010

出　　处：《地下空间与工程学报》2020年第6期1682-1688,共7页Chinese Journal of Underground Space and Engineering

基　　金：国家自然科学基金(41562014)。

摘　　要：为研究不同含水率黄土在一维冻结条件下温度场、冻胀量和水平冻胀力的变化特征规律及冻胀力与冻结温度之间的动态关系,选取兰州地区黄土进行了封闭系统下的一维冻胀试验。研究结果表明:土体的降温过程分为3个阶段,降温冻结初期各深度土体的温度下降速率较快;土体温度下降到0℃时降温曲线出现转折点,土层各深度降温速率曲线出现近乎平行于横坐标的平稳段;冻结后期各深度土体的温度下降速率较慢。冻胀量变化曲线按照变化趋势分为3个阶段:轻微冻缩阶段,快速发展阶段,拟稳定阶段,不同含水率的土体经历各阶段的时间有所不同。冻胀量随着土体含水率的增加而增大,本试验中含水率14%和20%的土体最终冻胀量分别为3.52 mm和8.23 mm。在相同土质和温度条件下冻胀力发展的起始温度相同,约为0.60℃,含水率不同的土体出现最大水平冻胀力的温度不同。最大水平冻胀力沿土体深度先增大后减小,最大值出现在相对深度0.6-0.8处。In order to study the relationship between temperature field,frost heave and horizontal frost-heave force and the relationship between frost-heave force and freezing temperature of loess with different moisture content under one-dimensional freezing conditio,the one-dimensional frost heaving test of the loess in Lanzhou area under the closed system was carried out.The research results show that the cooling process of the soil is divided into three stages.At the initial stage of cooling and freezing,the temperature drop rate of the soil at each depth is fast;when the temperature of the soil drops to 0℃,the cooling curve shows a turning point,and the temperature drop curve of each depth of the soil layer appears a plateau that is nearly parallel to the axis of abscissa;at the late stage of freezing,the temperature drop rate of each depth soil is slow.The frost-heave variation curve is divided into three stages according to the change trend:the slight frosting stage,the rapid development stage,and the quasi-stable stage.The soils with different water contents experience different times in each stage.The amount of frost heaving increases with the increase of soil moisture content.In this test,the final frost-heaving amount of soil with water content of 14%and20%is 3.52 mm and 8.23 mm,respectively.Under the condition of the same soil quality and temperature,the initial temperature of the development of frost heave force is the same,which is about 0.60℃,and the temperature at which the maximum horizontal frost-heave force occurs is different in soils with different water contents.The maximum horizontal frost-heave force first increases along the soil depth and then decreases,and the maximum value appears at a relative depth of 0.6-0.8.

关 键 词：冻土 冻胀特性 水平冻胀力 模型试验 

分 类 号：TU411.93[建筑科学—岩土工程]