Unsaturated Hydraulic Conductivity Characteristics Of Geotextiles

In arid or semiarid regions, geotextiles are always used in unsaturated conditions, so that the drainage ability depends on unsaturated hydraulic characteristics of geotextiles. Unsaturated hydraulic characteristics of two kinds of geotextiles were studied by carrying out capillary altitude tests, water-retention curve tests, and siphon tests. The effect of capillary altitude,water-retention and unsaturated hydraulic coefficient was discussed. The capillary altitude tests show that geotextiles with smaller equivalent opening size have bigger capillary altitudes. The water-retention curve tests indicate that suction decrease with the water content non-linearly, and geotextiles with smaller equivalent opening size have better water holding capacity. The siphon tests show that permeability coefficient decrease with suction non-linearly, and geotextiles with smaller equivalent opening size have better hydraulic conductivity in wider suction range. Under the condition of knowing the unsaturated hydraulic characteristics of geotextiles and the unsaturated hydraulic characteristics of the loess, we can simulate the different unsaturated seepage conditions about the loess and the geotextiles by using the numerical simulation software.There are three different unsaturated seepage situations, these conditions respectively for the loess,the loess and the geotextile of one kind and the loess and the geotexile of the other kind. According to the numerical simulation results,we can know that the geotextiles which are inclined in the loess can form the capillary barrier and the capillary barrier can prevent the water in the upper loess seep into the sublayer,besides the geotextiles can deduce the moisture in the loess.