Experimental study on optimal grid size of coarse-grained soil-grid considering the effect of gradation
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 dmax and grading area S.Creating 60 reinforced specimens by using four different grid sizes La 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,Sopt,that maximizes seismic performance when dmax and La are fixed.When the grid size remains constant Sopt increases logarithmically as dmax increases.Conversely,when dmaxis constant,Sopt decreases logarithmically as La increases.A quantitative model is developed to dmax describe the combined effects of dmax and La on Sopt.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.
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