非饱和原状和重塑Q3黄土渗水特性研究

为研究非饱和 Q₃ 黄土渗水特性，设计一套原状黄土取样设备，取得大尺寸原状竖直和水平土柱各 2 个；并制备 5 个干密度不同的重塑土样。对 9 个试样进行水平土柱试验，用 TDR 水分计和热传导吸力探头分别检测土样不同断面处的体积含水率和基质吸力。试验结果表明：土中裂隙的走向和干密度对入渗率均有影响。对于原状试样，浸水前期竖直试样入渗率要大于水平试样，湿润锋超过 50 cm 后，竖直和水平试样入渗率几乎接近一致。竖直与水平原状试样的非饱和扩散率主要差别在饱和度低于 0.6 的区域，饱和度高于 0.6 两者扩散率差别不大；对于重塑试样，低饱和度区域干密度对扩散率影响要大于高饱和度区域。同等干密度和含水率条件下，低饱和度区域重塑试样非饱和渗透系数大于原状试样；而高饱和度区域原状试样非饱和渗透系数大于重塑试样。取样方法和研究成果对同类工作具有重要参考价值。

Hydraulic conductivity of unsaturated undisturbed and remolded Q3 loess

In order to study the hydraulic conductivity of unsaturated Q3 loess,an equipment for sampling undisturbed loess is designed,four vertical and horizontal loess columns are acquired successfully and five remolded soil columns with different dry densities are prepared.The tests on horizontal soil columns of nine samples are carried out.TDR moisture meters and thermal conduction suction probes are embedded to monitor volumetric water content and matric suction in different sample sections.The results indicate that the infiltration velocity is influenced by crack direction and dry density of the soil columns.For the undisturbed loess samples,the infiltration velocity of vertical samples is greater than that of horizontal samples at the beginning stage of soaking tests.When the wetting front exceeds 50 cm,the infiltration velocities of vertical and horizontal samples get close to each other.The differences of diffusion coefficient between undisturbed vertical and horizontal samples exist distinctly below the saturation degree 0.6.When the saturation degree surpasses 0.6,the diffusion coefficients are nearly identical.As to the remolded loess samples,the effect of dry density on the diffusion coefficient mainly exists in the lower saturation degree area.Under the same dry density and moisture content,the unsaturated hydraulic conductivity of the remolded samples is greater than that of the undisturbed samples in the lower saturation degree area,however,in the higher saturation degree area,the unsaturated hydraulic conductivity of the undisturbed samples is greater than that of the remolded samples.The sampling method for the undisturbed loess and the research findings of those tests give some referential values to the same studies.