Abstract:

Geogrid, commonly used for reinforcement in rockfill dams, significantly enhances seismic performance when appropriate grid dimensions are selected based on particle size distribution. Investigating the variations in optimal grid dimensions influenced by particle size distribution is of great engineering importance. By employing the continuous grading equation, 15 sets of graded soils were developed by varying the maximum particle size d_max and grading area S. Creating 60 reinforced specimens by using four different grid sizes L_a to reinforce each soil. Subsequently, large-scale direct shear tests were performed on each specimen to quantitatively analyze the correlation between grading area and geogrid dimensions, aiming to optimize the seismic performance of reinforced coarse-grained soil. The experimental results show that there is an optimal grading area, S_opt, that maximizes seismic performance when d_max and L_a are fixed. When the grid size remains constant S_opt increases logarithmically as d_max increases. Conversely, when d_max is constant, S_opt decreases logarithmically as L_a increases. A quantitative model is developed to d_max describe the combined effects of d_max and L_a on S_opt. This model is integrated with engineering practices to propose an empirical formula based on indoor test results for predicting the optimal grid dimensions for the original grading of coarse-grained soil on-site.

Key words: coarse-grained soil, geogrid, particle grading, cyclic shear, optimum mesh size