基于湿润锋前进法的不同应力状态砂质黄土土柱渗流试验

由于试验装置的局限性,非饱和土渗透特性的研究大多未考虑应力对渗透系数的影响。为探讨水-力耦合作用下砂质黄土的渗透特性,自主研制了一套水-力耦合试验装置。采用湿润锋前进法探究了不同初始干密度和轴向力对非饱和渗透系数的影响,得到水-力耦合作用下非饱和黄土渗透性和轴向位移的演化规律。结果表明:(1)砂质黄土的渗透系数随基质吸力的增大而减小,在不同测试截面处渗透函数曲线出现分层现象;(2)土体的渗透系数随初始干密度和轴向力增大而减小;(3)随轴向力增大,不同初始干密度土柱的稳定渗透系数趋向一致;(4)砂质黄土具有较大的水敏性,在水-力耦合作用下土体结构破坏,导致湿化前后轴向位移差异较大。

Seepage experiments of sandy loess soil column with different stress states based on wetting front advancing method

Due to the limitations of the test apparatus,most of the studies on the permeability of unsaturated soil ignore the influence of stress on the permeability coefficient. In this paper,a hydro-mechanical coupling apparatus was developed independently, and the seepage soil column experiment was carried out on sandy loess with this apparatus. Wetting front advancing method was used to explore the effect of different initial dry density and stress on unsaturated permeability coefficient, and the evolution law of permeability and axial displacement of sandy loess under the hydro-mechanical coupling was obtained. The permeability coefficient of the soil column decreases with the increase of the matric suction and the permeability functions at different sections are hierarchical. The permeability coefficient of soil decreases with the increase of initial dry density and axial stress. As the axial stress increases, the stable permeability coefficients of soil columns with different initial dry densities tend to be consistent. Sandy loess has greater water sensitivity, and the soil structure is destroyed under hydro-mechanical coupling,resulting in a large difference in axial displacement before and after wetting.