非饱和土向上渗流试验仪的研制与应用

地下水(潜水)位上升,在黄土(非饱和土)中会产生一种特殊的渗流现象向上渗流。为了探索黄土中的向上渗流规律,研制了非饱和土向上渗流试验仪。试验仪器由补水装置、渗流装置、连接管及试验台等部件组成,可用来模拟不同水势压力(定水头压力)条件下潜水位上升的水土作用过程。该试验仪不仅可直接观察水在土中向上渗流的过程、渗流锋面形态及变化,而且可以获取渗流锋面位移-时间关系(渗流速度)、渗流压力-渗流速度关系等渗流特征参数,揭示向上渗流规律,服务于黄土灾害(滑坡、崩塌、地面沉降等)研究。基于此试验仪器,采取两组原状非饱和离石黄土,对其均分别进行定压力水头为1cm、5cm、10cm的向上渗流模拟试验,试验结果表明:试验仪器能够较好模拟定水头压力条件下潜水位上升的水土作用过程、直观再现水在土中的向上渗流以及获取所需的向上渗流特征参数,具有一定的应用前景及价值。

DEVELOPMENT AND APPLICATION OF UPWARD PERMEAMETER FOR UNSATURATED SOIL

Upward seepage, a special kind of seepage phenomenon, can be generated in the loess(unsaturated soil) on the rise of underground water(phreatic water) level. In order to explore the upward seepage law in the loess, the upward permeameter on unsaturated soil is developed. This experimental instrument consists of water replenishing device, seepage device, connecting pipe which connects the two devices and test bed. It can simulate the interaction between soil and water under different water pressure(constant head pressure) on the rise of water table. The tester can directly observe the process of water upward seepage in the loess, the shape and the change of seepage front and can obtain the relationship between seepage frontal displacement and time(seepage velocity),the relationship between seepage pressure and seepage velocity. Revealing the upward seepage law to serve the study of loess disasters(landslide, collapse, land subsidence and the like) is of great significance. On the basis of the experimental instrument, two sets of in-situ unsaturated Lishi loess are selected to do simulation. The constant pressure heads of the two sets of soil samples are 1cm, 5cm and 10cm. The experimental results show that the instrument can effectively simulate the interaction between soil and water under constant head pressure on the rise of water table, intuitively reproduce the water seepage in the soil and obtain the required upward seepage characteristic parameters. Also, the permeameter renders certain practical value and application prospect.