考虑干密度影响的压实黄土土水特征与渗透特性试验研究

Soil-water characteristics and permeability of compacted loess considering effects of dry density

为了研究干密度对压实黄土土水特征、渗透特性的影响,用一维瞬时土柱渗透仪开展了不同干密度压实黄土的常水头渗透试验,得到了入渗量、体积含水率、吸力时程线与土水特征曲线;利用瞬态剖面法计算了非饱和渗透系数,分别得到其与吸力和饱和度的关系曲线。结果表明:干密度增大,入渗量时程线趋于平缓,吸力和体积含水率时程线转折点后移,陡变段斜率增大,其变化规律可用5个时间段进行描述;水自试样底部流出稳定后,不同干密度试样皆未完全饱和,其最大饱和度随干密度增大而增大;干密度增大,土水特征曲线上移,渗透性曲线规律性下移。基于试验结果,分别建立了直接考虑干密度影响的土水特征和渗透性函数的归一化模型。

In order to investigate the influences of dry density on the soil-water characteristics and permeability of compacted loess, a one-dimensional instantaneous soil column infiltration instrument is used to carry out the constant head infiltration tests on the compacted loess with different dry densities, and the time-history curves of infiltration volume, volumetric water content and suction and the soil-water characteristic curves at the monitoring section are obtained. The unsaturated permeability coefficient is calculated by the transient profile method, and the relationship curves among permeability coefficient, suction and saturation are drawn respectively. The research results show that as the dry density increases, the time-history curves of infiltration tend to be flat, the turning point curves of the time-history of suction and volumetric water content move back, and the slope of the steep change section increases. Five time periods can be used to describe the change law. After the water flow from the bottom of the soil column is stable, the samples are not fully saturated, and the saturation increases with the dry density. As the dry density increases, the soil-water characteristic curve moves upward as a whole, and the function curves of permeability coefficient move downward as a whole. Based on the test results, the normalized models for the soil-water characteristic and permeability curves that directly consider the influences of dry density are established respectively.