土工格栅作为土石坝常用的加筋材料，根据颗粒级配采用适合的格栅网格尺寸可显著提高土石坝抗震性能，探究级配影响下最优网格尺寸变化规律具有工程意义。基于连续级配的级配方程，通过改变最大粒径dmax和级配面积S，设计15组级配土料，采用4组不同网格尺寸La对各个土料加筋，做成60组加筋试样。利用大型直剪仪对各个试样进行循环剪切试验，从而定量研究级配与能使加筋粗粒土抗震性能达到最优的土工格栅网格尺寸之间的关系。试验发现，当dmax及La一定时，级配面积存在一个最优值使抗震性能达到最佳，将此定义为最优级配面积Sopt；当网格尺寸一定时，Sopt 随dmax增大而增大，两者之间呈明显的对数关系；当dmax一定时，Sopt 随 La 增大而减小，两者之间也呈明显的对数关系。建立定量描述dmax和La对最优级配面积Sopt的耦合影响的计算模型，并结合工程实际，提出基于室内试验结果预测现场粗粒土原级配对应最优网格尺寸的经验公式。Geogrid

commonly used for reinforcement in rockfill dams

significantly enhancesseismic performance when appropriate grid dimensions are selected based onparticle size distribution. Investigating the variations in optimal griddimensions influenced by particle size distribution is of great engineeringimportance. By employing the continuous grading equation

15 sets of gradedsoils were developed by varying the maximum particle size dmax and grading area S. Creating 60 reinforced specimens by using fourdifferent grid sizes La toreinforce each soil. Subsequently

large-scale direct shear tests wereperformed on each specimen to quantitatively analyze the correlation betweengrading area and geogrid dimensions

aiming to optimize the seismic performanceof reinforced coarse-grained soil. The experimental results show that there isan optimal grading area

Sopt

that maximizes seismicperformance when dmax and La are fixed. When the grid size remains constant Sopt increaseslogarithmically as dmax increases. Conversely

when dmax is constant

Sopt decreases logarithmically as La increases. A quantitativemodel is developed to dmax describe the combined effects of dmax and La on Sopt.This model is integrated with engineering practices to propose an empiricalformula based on indoor test results for predicting the optimal grid dimensionsfor the original grading of coarse-grained soil on-site.