Study On The Properties Of Strecthed Geogrids

The stretched geogrid was chosen as the major object studied in this paper. The properties of the geogrids, including the mechanical properties, the creep properties, installation damage, were systemically investigated, which significantly affect the design strength of geogrids for engineering application.Various punchers of different sizes were chosen for the test of the mechanical properties, in which the draw temperature, draw speed, draw ratio were designed, in order to study the effects of punching and stretching technical factors on mechanical properties of geogrids. And then the processing was simulated. It is shown that, the tensile strength increases firstly and then decreases, while the elongation continuously decreases and the strength at 2% and 5% elongation continuously increases, with the draw temperature decreasing, or the draw speed, the draw ratio increasing. It seems that there are similar regulations between the effect of the draw temperature, the draw speed and the draw ratio on the mechanical properties of the geogrids.DSC results show that crystallinity of the geogrids ribs is different owing to various stretching technical factors, and that the crystallinity of the stretched sample is larger than the unstretched one. The crystallinities of the sample are similar at lower draw temperature and higher draw speed, which show that there is correlation among the stretching factors.The systematic experiments were designed in order to study the creep properties of stretched geogrids. And the creep equations were simulated with the creep curves of geogrids. It is shown that the cubic polynomial equations are best in the simulation of the creep properties of the geogrids. The creep behaviors of the geogrids were systematically studied with different temperature and load, with the creep reduction factors for EGRB stretched geogrids determined.The full-scale site damage tests of EGR geogrids were performed, with five kinds of grading fill materials and three types of compaction conditions. The installation damage properties of stretched geogrids were systematically. As a result, the site damage factors were determined applying to EGR geogrids for engineering design.