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围绕非均质条件下河流包气带水分运移,选择渭河河漫滩开展原位试验。在渭河原位试验点开挖7 m×1 m×2.8 m的探坑,以一侧剖面为研究面,刨光成垂直平面并对剖面做保护工作,方便观测。在不同层位按不同深度、在不同岩性的层位上打孔,分别安装MP-917时域反射仪与水银压力计,监测含水率及地下水压力势,并采用自制Bauwer渗水仪做持续5 d的有压入渗试验,研究非均质条件下河流包气带水分运移规律及入渗速度与水头高度的关系。结果表明,包气带介质含水率分布与包气带结构有关,受岩性渗透系数制约,其中弱透水层的存在阻滞了水分的运移,包气带很难达到饱和,在弱透水层以上形成上层滞水并以非饱和流形式入渗。入渗速度随水层的厚度增大而增大,且入渗速度与水头高度呈对数关系。
Focusing on the moisture transport in the aeration zone of the river under heterogeneous conditions, the in-situ test of the Weihe River floodplain was selected. Excavation pit of 7 m × 1 m × 2.8 m was drilled at the in-situ test point of Weihe River. One side profile was taken as the research plane, and the plane was sliced into a vertical plane and the profile was protected so as to facilitate the observation. At different depths, holes were drilled in layers of different lithologies. MP-917 time-domain reflectometer and mercury manometer were installed respectively to monitor the water content and groundwater pressure potential. The homemade Bauwer water-immersion instrument was used for continuous 5 d pressure infiltration test to study the heterogeneity of water vapor movement of the aeration zone and the relationship between infiltration velocity and head height. The results show that the distribution of moisture content in the aeration zone is related to the structure of the aeration zone and is controlled by the lithologic permeability coefficient. The presence of the impermeable layer hinders the migration of water and the aeration zone is difficult to reach saturation. Above the formation of the upper stagnant water and infiltration of unsaturated flow. The infiltration velocity increases with the thickness of the water layer, and the infiltration velocity is logarithmically related to the head height.