Micro-mechanism of the interaction between sand and geogrid transverse ribs

Abstract

ABSTRACT: To study the interaction between sand particles and geogrids, pullout tests were performed on one type of geogrid in Pingtan medium sand. The sand motion around the ribs was captured by high-resolution digital camera and CCD camera. The images were analysed with the aid of digital photography measurement and micro-image analysis. Microscopic particle motion and displacement fields around the transverse ribs were then obtained to verify the macro behaviour of the sand–rib interaction. It was found that the thickness of shear band increases with the normal stress applied, and the shear zone is asymmetrical to the soil–rib interface. A near wedge shape shear zone was observed by analysing the shear strain around the ribs, which indicated that a punching shear failure mechanism may be applicable to the tested geogrid in medium-dense sand. Comparison of various models for bearing capacity of geogrids shows that the size and shape of bearing members should be considered in the calculation of bearing resistance of geogrids.