Abstract:In order to improve the embedding effect of geogrid on reinforced aeolian sand, in this paper, four kinds of geogrids with new transverse ribs are designed by changing the thickness and shape of transverse ribs on the basis of ordinary biaxial geogrid. The pull-out test and DEM-FDM coupling method are used to study the influence of grid transverse ribs on the reinforcement effect and mechanism of aeolian sand. The reinforcement efficiency is introduced to evaluate the interface resistance characteristics of geogrid and soil, and the optimal geogrid transverse rib shape of reinforced aeolian sand is determined. The relationship between pullout force and pullout displacement and reinforcing efficiency under different thicknesses and shape of transverse ribs are analyzed at the macroscopic level. The evolution law of contact force chain and displacement field is studied at the mesoscopic level. The results show that the shape and thickness of the transverse ribs have a great influence on the shear strength of the reinforcement-soil interface. The pull-out force of the four new types of geogrids is about 1.1-3.6 times that of the ordinary biaxial geogrid. Combined with the concept of the material usage ratio of the geogrid, it is found that the rhombus transverse rib geogrid has the highest reinforcement efficiency. Through microscopic analysis, it is found that the strong contact force chain at the pull-out end is obviously denser during the pull-out process. Compared with the ordinary biaxial geogrid, the evolution trend of the contact force chain of the rhombus transverse rib geogrid is more significant, and the strong force chain is more denser, which indicated that the change of the shape and thickness of the transverse rib can mobilize more soil particles to resist the pull-out of the geogrid. During the pullout process, the displacement of the soil particles is lagging behind the displacement of the geogrid. Under the same pullout displacement, the participation of the surrounding soil of the rhombus transverse rib grid is higher than that of the biaxial geogrid during the pullout process, and the disturbance to the soil is also greater. The findings of this study can offer a significant reference for the development of new transverse rib geogrids and the reinforcement design of desert railway subgrades.
