EXPERIMENTAL STUDY ON THE DRAINAGE PERFORMANCE AND PORE STRUCTURE OF THE CAPILLARY WATER-CONDUCTING MATERIALS

In this study,5 different types of capillary water-conducting materials(i.e.,COOLPASS,COOLPLUS,COOLMAX,SHCOOL,and Ordinary Mesh Fabrics) are selected for water absorption and drainage test,NMR test,and capillary rising test to investigate their drainage performance and pore structures. The purpose is to reveal the mechanism of capillary water absorption and drainage performance,and as a reference for finding or producing a geotextile that can be applied to some unsaturated soil with high moisture content in the country. Results show that these capillary water-conducting materials have good water absorption and drainage effect in both soil and water. Through the drainage test of capillary water-conducting materials in water,it is found that capillary rising distance and air relative humidity affect the water removal effect. Generally,we divide these five kinds of fabrics into two levels by their performance: the COOLPASS,COOLMAX and Ordinary Mesh Fabrics have the best drainage performance,while the performance of SHCOOL and COOLPLUS are slightly weaker. The pore sizes of COOLPASS,COOLMAX and Ordinary Mesh Fabric are about 53.4 μm and the pore size of SHCOOL and COOLPLUS are 37.8 μm through the NMR test. According to the NMR test of these materials,it is found that the ability of drainage is related to their pore diameters and distribution characteristics. Considering the two processes of capillary absorption and evaporation drainage of the water-conducting capillary materials,the drainage effect of the material with a large pore diameter and sparse distribution is better in unsaturated soil,the moisture content of the soil sample decreases by 2.19% more than the soil sample without capillary drainage material under the same condition. In the capillary rising test,the capillary rise height of COOLMAX is the highest. Therefore,the water absorption capacity of capillary water-conducting material is related to its pore distribution characteristics,the denser the pore distribution is,the stronger the water absorption capacity is.