摘要:
渗透系数是研究实际工程渗水问题的关键参数之一。以往对于非饱和土渗透系数的试验研究中，增湿工况较为单一，极少考虑竖向附加应力的影响。基于此，开发了一套一维垂直土柱试验装置以弥补这一缺陷。该装置主要由试验台架、土柱筒、竖向加载装置、供水装置、水分传感器、张力传感器以及数据采集系统等组成，可模拟竖向附加应力作用下降雨、积水入渗、毛细上升工况，可测定增湿过程中水的入渗量与浸润峰时程线、土柱竖向变形以及不同截面的体积含水率与基质吸力的时程曲线，基于瞬态剖面法可获得不同截面处增湿时土的非饱和渗透系数与吸力关系。最后，以兰州Q3非饱和粉质黄土为例，初步开展了不同竖向附加应力作用下土柱积水入渗试验，分析入渗量、湿润锋、体积含水率、吸力及竖向变形时程线变化规律，获取渗透系数与吸力关系的渗透函数变化规律，通过对比类似试验结果，表明试验结果符合渗水规律，验证了研制土柱仪的有效性，但其可靠性还需进一步研究。本试验装置为不同工况下非饱和土体变形、水分迁移规律及渗透特性研究奠定基础，并获得相应试验参数。
Abstract:
The permeability coefficient is one of the key parameters for studying the actual engineering water seepage problem. In the past, in the experimental study on the permeability coefficient of unsaturated soil, the humidification condition was relatively simple, and the influence of vertical additional stress was rarely considered. Based on this, a one-dimensional vertical soil column test device was developed to compensate for this defect. The device is mainly composed of test bench, soil column cylinder, vertical loading device, water supply device, moisture sensor, tension sensor and data acquisition system, which can simulate the test conditions of rainfall, water infiltration and capillary rise under vertical-additional-pressure, and measure the infiltration quantity and wetting front time-history curve, the vertical deformation of soil column, the volumetric moisture content of different sections and the time-history curve of matric suction. Based on transient profile method, when the humidifying the relation between unsaturated permeability coefficient and suction at different sections can be obtained. Finally, taking Lanzhou Q3 unsaturated silty loess as an example, preliminary experiments on soil water infiltration under different vertical additional stresses were carried out to analyze the infiltration, wetting front, volumetric water content, suction and vertical deformation time history. The variation law of the line, the change law of the permeability function of the relationship between the permeability coefficient and the suction force is obtained. By comparing the similar test results, the test results are consistent with the water seepage law, and the effectiveness of the soil column instrument is verified. However, the reliability needs further study. The test device lays a foundation for studying the characteristics of deformation, water migration and permeability of unsaturated soil under different working conditions, and obtains corresponding test parameters.
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