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.