عنوان مقاله [English]
In order to increase the efficiency of reinforcements in a reinforced soil structure, the granular soils are usually used. However, in the most situations, we have to transfer granular soils from the borrow area, usually
far from the site of the soil structures. This will impose a considerable amount of money to the project. Therefore, in this research, just a layer of coarse-grained soil, surrounding the reinforcement layer is used and the
remained volume was filled with the fine-grained soils or the soils that exist in the project site. This experimental study is performed for the selected thicknesses of coarse-grained soil surrounding the reinforcement. Furthermore, the numerical analysis for these pull-out tests was conducted using the finite element code, PLAXIS3D Tunnel. Finally, the experimental and numerical analysis results for the variety of coarse soil thicknesses were compared and the optimum thicknesses for coarse-grained soil are presented. According to the
results, the pull-out resisting force increases with increasing the coarse layer thickness; in addition, the Grid-Anchor endures more pull-out resisting forces as compared with the usual geogrid. According to the experimental
results, 10 centimeters coarse layer (i.e. the thickness of 5 centimeters for the top and the thickness of 5 centimeters for the bottom layer of the reinforcements) was found as optimum thickness of surrounding layer for the 5 kPa surcharge. Other findings of this research can be as follows: when the reinforcements begin to move against the soil surrounding them, the pull-out resisting force decreases due to the decrease in friction between the soil and the reinforcements. On the other hand, as the thickness of coarse layer around the reinforcements increases, a hardening state in the force-displacement curve of these reinforcements was observed. This situation is more visible for Grid-Anchor in comparison with the usual geogrid. Having compared the numerical
and experimental results, there is a suitable conformance between them.