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目的：建立含水率与介电常数间的经验关系模型是利用时域反射（TDR）技术测试土体含水率的关键。通过收集并建立包含45种土样418个试验数据点的数据库，提出一个土体质量含水率与表观介电常数间的经验公式，分析经验公式误差随土体类型、干密度、击实功、孔隙水电导率和温度等因素的变化规律，并提出考虑干密度影响的修正方法。 创新点：1.基于电磁波相互作用理论，直接建立土体质量含水率和介电常数间的关系模型；2.通过数据拟合得到通用型经验公式，可在现场无标定快速高效地实现含水率测试。 方法：1.通过理论分析，直接建立土体质量含水率和介电常数间的关系模型（公式（9））；2.通过试验数据收集和回归分析得到通用型经验公式（图2和公式（10））；3.通过影响因素分析，对公式的适用性和有效性进行分析（图3~7）。 结论：1.该经验公式对常见的土体类型均能给出误差在±0.05 g/g以内的结果；2.在1.3~2.3 g/cm3的干密度范围内，该经验公式具有较好的适用性；在工程中常见的击实功和孔隙水电导率变化范围内，含水率测试精度可满足工程要求；4~30°C温度变化范围对本经验公式的计算结果无明显影响；3.利用该经验公式，对于特殊场地，可以不通过标定实现 TDR 现场测试，具有较好的实用性。“,”The crucial point in calibrating soil water content using the technology of time domain reflectometry (TDR) is to establish the relationship between the apparent dielectric constant and the water content. Based on a database, which included 45 kinds of soil samples and 418 data points from our own test data and relevant literature, an empirical calibration equation is pro-posed. Additionally, the influence of soil type, dry density of soil, compaction energy, pore fluid conductivity, and temperature on the calculated result for water content was also analyzed. Results show that the equation can offer an error of ±0.05 g/g for most soils encountered in geotechnical engineering.However, the estimation error given by the empirical equation becomes significant for soils with dry density less than 1.3 g/cm3, so the equation was modified to consider the influence of dry density. Both of the empirical equations can be used to test gravimetric water content using the TDR method conveniently and efficiently without calibration.