Study On Tensile Properties Of Warp Knitted Geogrid

Warp-knitted geogrids,as a kind of geosynthetics with reinforcing function,have been widely used in various engineering fields,especially in soft foundation reinforcement,because of their advantages of high strength,low strain,light weight and anti-aging.In China,the application and research of warp-knitted geogrids started relatively late,and more research on the engineering application of geogrids,while the experimental research on the mechanical properties of geogrids is relatively less.In view of the current research situation of warp-knitted Geogrids in China,the unidirectional tension test of warp-knitted geogrids is carried out in this paper,in order to make a reasonable evaluation of the tension characteristics of warp-knitted geogrids.Firstly,the research results of warp-knitted geogrids tension test conducted by scholars at home and abroad are analyzed,and the classification and function of geosynthetics and the concept,classification and engineering application of geogrids are summarized and discussed.The tensile mechanism of warp-knitted polyester geogrids is explained from both micro and macro perspectives,and the structural model,plastic deformation and engineering characteristics of geogrids are analyzed.In this paper,the unidirectional tensile test method is used to study the tensile properties of warp-knitted polyester geogrids,and the effects of tensile rate and coating technology on the tensile properties of warp-knitted polyester geogrids are analyzed and summarized.Aiming at the effect of tensile rate on the tensile properties of warp-knitted polyester geogrids,the tensile properties of warp-knitted polyester geogrids with four strengths were analyzed by different rates of tensile.The experimental results show that the tensile strength and secant modulus of warp-knitted geogrids with the same strength increase with the increase of tension rate,while the peak strain decreases with the increase of tension rate.Through regression analysis,the relationship between tensile strength,modulus and tensile rate under certain strain was summarized.The tensile failure phenomena of geogrids at different rates are compared,and two failure modes are proposed.Tensile tests of warp-knitted geogrids with different strength were carried out.The results of tensile strength tests at 2% and 5% strains show that the tensile strength of warp-knitted geogrids at 2% and 5% strains is about 16%-25% and 29%-49% of the tensile strength.Aiming at the influence of coating technology on the tensile properties of warp knitted polyester geogrids,the effects of kiln temperature,transmission speed and coating material ratio on the tensile properties of warp knitted geogrids were analyzed.The test results show that the tensile strength,peak strain and modulus increase first and then decrease during the drying process from 90 to 100 and then to 110 degrees centigrade;the tensile strength decreases slightly when the transfer rate increases from 2.355 m/min to 3.369 m/min,the tensile modulus decreases,and the peak strain decreases;the tensile strength decreases slightly with the increase of the ratio of PVC slurry to water from 1:1 to 2:1.The tensile modulus decreases and the peak strain increases significantly with the decrease of strain.The failure phenomena of geogrids under different coating processes are compared,and two failure modes are proposed.