The hydraulic conductivity of unsaturated soils can span several orders of magnitude. The measurement of hydraulic conductivity over a wide suction range is a challenging task for decades. In this study, numerical tests are carried out to check the assumption, error sources, and applicable conditions of the wetting front advancing method and instantaneous profile method. Based on the numerical test results, a digital wetting front advancing method is proposed to measure hydraulic conductivity of unsaturated soils in the relative high suction range and the traditional instantaneous profile method is found to be robust in measuring hydraulic conductivity in the low suction range, e.g. for soil with a degree of saturation above 0.9. Further, a combination of the digital wetting front advancing method and the traditional instantaneous profile method is implemented in the same soil column test and leads to an accurate soil hydraulic conductivity function over a wide suction range. The proposed method is applicable to various soil types and the test duration is only 1 ~ 5 days, thus makes the measurement of hydraulic conductivity a routine experiment for unsaturated soil mechanics.

非饱和土壤的导水率可以跨越几个数量级。几十年来，在大吸力范围内测量水力传导率是一项艰巨的任务。在这项研究中，进行了数值测试，以检查润湿前沿推进方法和瞬时剖面方法的假设，误差来源和适用条件。基于数值试验结果，提出了一种数字化润湿前移法来测量相对高吸力范围内的非饱和土壤的水力传导率，而传统的瞬时剖面法被认为在低吸力范围内能够有效地测量水力传导率，例如饱和度高于0.9的土壤。更多，在同一土壤柱试验中将数字湿润前沿推进方法与传统瞬时剖面方法结合使用，可在较宽的吸力范围内实现精确的土壤水力传导功能。该方法适用于各种土壤类型，测试持续时间仅为1〜5天，因此使水力传导率的测量成为非饱和土力学的常规实验。