Laboratory simulation of installation damage of a geogrid

A series of laboratory cyclic loading tests was performed to investigate the effects of load intensity and particle size of aggregates on installation damage of a flexible geogrid. Stress–strain characteristics of the damaged flexible geogrid are also compared with those obtained from some full-scale tests reported in the literature. The test results were as follows. The load intensity and particle size have major influences on the installation damage of the flexible geogrid investigated. A relatively small particle size as specified in a standard laboratory test (DD ENV ISO 10722-1) may generate unconservative results when larger particle sizes dominate in the infield soils. Load intensities ranging between 400 and 900 kPa induce similar amounts of strength loss of the geogrid compared with that obtained in the full-scale field tests. A change in loading frequencies between 0.1 and 3.0 Hz introduces no measurable difference in the damage of the geogrid. The use of loading cycles (N) greater than 200 introduces no further damage in the geogrid when compared with the damage using N = 200. The reduction in tensile stiffness at 5% strain is significantly lower than the reduction in ultimate strength for the damaged geogrid. Results of visual examination of the damaged geogrid show that damage evaluations based on visual inspection of a retrieved sample are feasible only when a calibration curve presenting a relationship between the number of damaged points and the strength loss for specific site and geogrid conditions has been established in advance.