考虑尺寸效应的根河粉质黏土冻胀试验研究

Experimental Study of Size-Effect on the Frost Heave Characteristics of Genhe Silty Clay

为研究冻胀试验的尺寸效应,对三种不同尺寸的根河粉质黏土饱水试样在-10℃、-15℃、-20℃温度下分别进行了封闭条件下冻胀试验,研究了试样尺寸、环境负温对根河粉质黏土的冻胀量、冻胀率及水分分布规律的影响。试验结果表明:在相同的环境温度和相同冻结时间下,随着试样高度的增加,冻胀量增大,而冻胀率减小,冻胀率与试样高度的线性关系随着温度的降低而减小;相同尺寸试样在不同负温环境下,降温梯度越大,冻胀量越小;封闭系统中,试样冻结后出现水分重分布,而且在环境温度与试样截面面积相同时,高度越大,上部与下部土层含水率差值越大,阐明了冻胀机理以及原位冻胀过程中试样的水分分布规律。根据试验结果,联立冻胀率与试样高度的线性方程与冻胀率公式揭示了冻胀量与试样高度二次函数关系,为冻害防治措施中土体冻胀参数的准确获取提供了定量依据。

To study the influence of size-effect on frost heave test,Genhe silty clay saturated samples with three different sizes were formulated to conduct frost heave test under closed conditions at-10℃,-15℃,and-20℃.The impact of sample size and environmental negative temperature on the frost-heave amount,frost heaving ratio and water distribution of Genhe silty clay was studied.Based on the test results and data analysis,the major findings are achieved as follows.The frost-heave amount increases with increase of sample height.While,the frost heaving ratio decreases with increase of sample height.The slope of the linear relationship between the frost heaving ratio and sample height decreases with decrease of temperature.The frost-heave amount of the same-size samples would decrease with decrease of the ambient temperature.In closed systems,the moisture redistribution occurs after freezing with the same ambient temperature and cross-sectional area of the sample,the difference of soil moisture content between the upper and lower layers would increase with increase of height.It clarifies the mechanism of frost heave and sample water distribution during in-situ frost heave.In addition,the simultaneous linear equation of frost heaving ratio and sample height and the formula of frost heaving ratio reveal the quadratic function relationship between the frost-heave amount and the height of the sample.The major findings can be used as an accurate acquisition of frost heaving parameters of soil in the prevention of frost damage.