Abstract: In order to improve safety and stability of fine tailings dam, a method of strengthening its mechanical properties by traixial geogrid reinforcement was put forward, and pull-out tests of biaxial and traixial geogrid under different conditions were carried out with fine tailings as fillers. Then, difference in reinforcement effects of these two geogrids were analyzed, and influence of relative density, water content and normal stress on interface characteristics of traixial geogrid were emphatically studied. The results show that traixial geogrid has better reinforcement effect than biaxial one, and interface strength parameters show difference of pseudo-friction angle. Moreover, the higher normal stress is, the better reinforcement effect of traixial geogrid will be. It is also found that increase of relative density significantly improves interfacial friction strength, and pseudo-cohesion and friction coefficient ratio monotonically increase along with relative density while apparent friction angle changes little. Interfacial friction strength at natural water content is greater than that at saturated water content. The former has 1.28 times of the latter's pseudo-cohesion, while pseudo-friction angle are approximately equal.

Key words: traixial geogrid, fine tailings, interface characteristics, pull-out tests, relative density, water content