Abstract: In order to study the mechanical properties of the reinforced interface between geotextile and fine tailings sand, we carried out pull-out tests on geogrid and geotextile under different test pull-out rates and different vertical pressures with varying moisture content of tailings sand. By comparing the pull-out test results of geogrid and geotextile under the same conditions, we conclude that geotextile has stronger reinforcement effect on fine tailings sand, and when vertical pressure is higher, the difference between the reinforcement effect on geotextile and geogrid is larger. With the rising of moisture content of tailings sand, the peak value of interfacial shear stress drops obviously: the interfacial shear stress at a moisture content of 1.2% is 1.5 times that when moisture content is 8.4%. Apparent cohesion increases at first but then decreases, with the peak value appearing near the optimal moisture content, whereas interfacial friction angle reduces rapidly at first and then declines slowly afterwards. With the augment of pull-out rate, the peak value of interfacial shear stress climbs slowly, and the apparent cohesion increases at first and then decreases, while the interfacial friction angle decreases at first and then increases. Under all working conditions, the peak value of shear stress increases linearly with the rising of vertical pressure.

Key words: geotextile, geogrid, pull-out test, reinforcement properties, moisture content of tailings sand