Abstract: The interface characteristics between prestrained geogrid and sand cushion were studied through a serious of pullout tests. The experimental program was divided into two parts, the influence factors, such as, normal stresses, cushion thickness and initial strain, on the interface characteristics of prestrained reinforcement were investigated by comparing the results of the comparative analysis. Under the low normal stress condition, the results showed that the prestrained geogrid and the conventional geogrid have little differences on the peak value of tension resistance when the thickness of sand cushion is 5 cm. The tensile stress of the prestrained geogrid is much higher than that of the conventional geogrid and the strain softening phenomenon is becoming obvious with the increase of the normal stress. When the normal stress is 50 kPa, the increase of the thickness of the sand cushion has an improvement to the tension resistance. When the thickness reaches 15cm, the effect is obviously reduced, and the strain softening will occur on the geogrid with a high prestrain level. Finally, the envelope of the shear strength of the interface is obtained by fitting the experimental data. It is concluded that the prestrained reinforcement can significantly increase the coefficient of quasi friction between the geogrid and the sand cushion and reduce the quasi interface cohesive force at the same time and provides theoretical basis for the popularization of prestrained reinforcement method.

Key words: Pre-Strained Geogrid, Reinforced Sand Cushion, Pullout Tests, Interface Characteristics