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摘要: 现有的土水特征曲线(SWCC)滞后性的研究多针对重塑土，原状黄土土水特征曲线滞后性特征的研究较少。为研究全吸力范围内原状黄土的滞后特征，以泾阳马兰黄土(L1)和离石黄土(L5)为研究对象，采用压力板仪和滤纸法测定增湿和减湿SWCC，采用压汞法测定孔隙分布特征，X衍射分析矿物成分。结果表明，在压力板仪测试基质吸力范围内(0~600 kPa)，滤纸法和压力板仪测定的SWCC具有一致性，且在减湿过程中两种方法的测试结果更为一致。滤纸法测得的全吸力范围(0~30 000 kPa)内，黄土SWCC滞后性存在三段性特征。即在天然含水率(L1 14.2%、L5 17.3%)附近，黄土SWCC几乎无滞后性；含水率高于天然含水率一定范围(L1大于19.2%、L5大于18.3%)，存在极为明显的滞后性；低于天然含水率一定范围(L1小于11.2%、L5小于15.4%)，存在弱滞后性。天然状态下反复干湿循环，导致黄土SWCC在天然含水率附近无滞后性；黄土限制孔隙对墨水瓶效应的增益作用，导致高含水率下黄土SWCC呈强滞后性；黏土矿物的水合作用，导致低含水率下SWCC呈弱滞后性。Abstract: There are few studies on hysteresis of soil and water characteristic curve(SWCC) of intact loess, and most of the existing studies focus on remolding soil samples. In order to study the hysteresis characteristics of intact loess in the full suction range, Malan loess (L1) and Lishi loess (L5) in Jingyang were taken as the research objects, their wetting and drying SWCCs were determined by filter paper method and pressure plate instrument. And their pore distribution and mineral composition were measured by mercury intrusion method and X-ray diffraction, respectively. The results show that the SWCCs measured by filter paper method and pressure plate instrument are consistent in the range of pressure plate instrument (0~600 kPa), and the results of two methods are more consistent in the process of drying. Within the total suction range (0~30 000 kPa) measured by filter paper method, the hysteresis of SWCC is characterized by three stages. That is, in the vicinity of natural water content (L1 14.2%, L5 17.3%), SWCC of the two layers of loess has almost no hysteresis; the water content is higher than a certain range of natural water content (L1 is greater than 19.2% and L5 is greater than 18.3%), and there is extremely obvious hysteresis; lower than a certain range of natural water content (L1 is less than 11.2% and L5 is less than 15.4%), there is a weak hysteresis. Repeated drying and wetting cycles under natural conditions result in no hysteresis of SWCC near the natural water content; the potentiation of limited pores on the ink-bottle effect leads to strong hysteresis at high water content; the hydration of clay minerals results in a weak hysteresis at low water content.
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