不同干密度下非饱和土土-水特征曲线

来源期刊:中南大学学报(自然科学版)2017年第3期

论文作者:陈宇龙 内村太郎

文章页码:813 - 820

关键词:非饱和土;土-水特征曲线;干密度;滞后现象

Key words:unsaturated soil; soil-water characteristic curve; dry density; hysteresis

摘    要:对吸湿与脱湿过程中引起非饱和土土-水特征曲线进行分析,观察不同密度土样的土-水特征曲线与滞后现象。利用Fredlund and Xing的土-水特征曲线模型对试验数据进行拟合,得到模型拟合参数与土-水特征曲线参数的定量关系。研究结果表明:进气值随着参数a的增大而线性增大,残余基质吸力随着参数m的增大而呈幂函数减小,减湿率随着参数n的增大而呈指数减小。干密度对土-水特征曲线有显著影响。随着干密度增大,残余基质吸力与进气值及进水值增大,减湿率减小,滞后现象的显著程度降低。瓶颈效应、不同的接触角和空气体积是造成滞后效应的主要因素。

Abstract: Drying and wetting soil-water characteristic curves (SWCCs) for two sandy soils were investigated to research the effects of dry density on the SWCCs and hysteretic behaviors. Drying and wetting SWCCs were obtained for two sandy soils with different dry densities. The test data were best-fitted using the Fredlund and Xing equation. The results show that the fitting parameter a increases linearly with the increase of the air-entry value of the SWCC, the fitting parameter m decreases with the increase of the residual suction of the SWCC and the fitting parameter n also decreases with the increase of the slope of the SWCC. With the increase of parameter a, the air-entry value increases linearly; with the increase of parameter m, the residual suction decreases in power function, and with the increase of parameter n, the slope of drying SWCC decreases in exponential function. The dry density has significant effects on the soil-water characteristic curve. With the increase of dry density, the residual suction, air-entry value and water-entry value increase, and both the slope of drying SWCC and the hysteresis decrease. The hysteresis is mainly attributed to the ink-bottle effect, the contact angle effect and entrapped air.

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