摘要
目的:综合使用HYPROP和WP4C两种仪器,探索采用蒸发法和冷镜露点法测量大吸力范围的水-土特征曲线,并采用收缩曲线对土体变形进行修正。方法:1.采用HYPROP仪器,在0～100 kPa吸力范围内测量土体的水-土特征曲线。2.当吸力大于600 kPa时,采用WP4C仪器,测量土体的水-土特征曲线。3.采用传统张力仪吸力板仪器,在0～500k Pa吸力范围内测量土体的水-土特征曲线。4.采用Satyanaga et al.(2017)公式,对实验数据进行拟合。5.采用HYPROP仪器直接测量土体的非饱和渗透系数。6.采用蒸发法,获取干缩曲线。结论:1.采用Satyanaga et al.(2017)公式,对实验数据进行拟合,拟合参数直接关联到进气值、拐点及方差。拟合结果显示,不同仪器所收集的水-土特征曲线的数据相互吻合,为水-土特征曲线的实验测量提供了更大的吸力范围。2.采用HYPROP仪器测量的非饱和渗透系数和采用传统改装的非饱和三轴实验数据基本吻合,因此,HYPROP可以作为在低吸力范围内(<100 kPa)测量非饱和渗透系数的有效仪器。3.当进气值小于100 kPa或者大于500 kPa时,综合采用HYPROP和WP4C可以有效缩短实验周期。
1 Introduction Fredlund and Rahardjo(1993)indicated that the behavior of unsaturated soil is significantly dependent on its soil-water characteristic curve(SWCC).There are many conventional methods for determining SWCC.Tempe and pressure plate apparatuses are commonly utilized in the laboratory to measure it(Zhan et al.,2007;Fredlund et al.,2012;Rahardjo et al.,2012;Cai et al.,2014).A Tempe cell is used to generate SWCC up to 100 kPa since it is provided with 1 bar(1 bar=1×105 Pa)high air-entry disc(Kassim et al.,2012;Rahardjo et al.,2019).A pressure plate cell(provided with a 5 or 15 bar high air-entry ceramic disc)is used to establish SWCC at suction ranges from 100 to 1500 kPa in combination with SWCC tests using the Tempe cell.These methods are known to be reliable for SWCC determination;however,they are tedious and time consuming(Fredlund,2007).
