Predicting Maximum Horizontal Displacement of the Wall and the Maximum Tensile Force in Reinforcements for Geogrid Reinforced Soil Wall under Overturning Mechanism

Soil reinforcement is a new technique to improve the mechanical properties of soil. Geosynthetic reinforced soil walls are usually designed based on limit equilibrium methods, ignoring the effects of foundation, reinforcement stiffness, facing, and other parameters. However, design procedures do not consider the deformation of the walls explicitly. Recently, numerical methods are used for the design and analysis of reinforced soil walls, and the programs written on this basis are used. Usually in limit methods, design of reinforced soil structures control for external stability or total stability or internal stability. After design of reinforcement elements, the overall stability of wall, i.e. overturning, sliding, and bearing capacity should be controlled. But in numerical methods, stress distribution and deformation can be achieved in reinforced soil walls. In this study, the finite difference method is used to perform analysis. According to the deformation manner of the wall and boundary conditions imposed on the structure in the reference study, so that the wall is joint at the heel (wall cannot slide) and taken into account its foundation in the rigid (insufficient bearing capacity does not happen), it can be said that obtained results of this modeling are used only for the overturning mode. In this numerical study, the effect of various system parameters on the performance of the wall, especially the maximum tensile force in the reinforcements and the horizontal displacement of the wall, is merely investigated for the external overturning instability mode. The important parameters of reinforced soil wall structure were studied including the reinforcement stiffness (J), the backfill soil friction angle (∅), the elasticity modulus of backfill soil (Es), the facing wall rigidity (EI), the reinforcement length (L), and wall height (H). Among investigated parameters, the most important parameters effective on the amount of deformation of the wall and maximum tensile force in reinforcements are reinforcement stiffness (J) and backfill soil friction angle (∅) regarding the material properties, respectively; other parameters do not have significant effect on the cases studied. The effect of stiffness on the maximum tensile force in the reinforcements is minimal and negligible. In the wall geometry which includes the reinforcement length (L) and wall height (H), the reinforcement length was the most effective and the most important factor to design reinforced soil walls. Based on the numerical results, the best range of L/H ratio to design reinforced soil walls is between 0.5 and 0.8 since for L/H ratio equal to 0.8 and more, the horizontal displacement of the wall is considered almost the same. Due to the importance of the project and the cost, it is suggested to consider L/H equal to 0.7. In this numerical study, curves are provided for predicting the maximum horizontal displacement of the wall and the maximum tensile force in the reinforcements. The numerical analyses show that there is a particular pattern between the maximum horizontal displacements of the walls and maximum tensile forces in the reinforcements. The results are presented in the form of graphs; using these graphs, the maximum horizontal displacement of the facing wall and the maximum tensile force in the reinforcement for walls with different heights can be predicted.