Method of gravel grading design for high-speed rail subgrade

The invention provides a method of a gravel grading design for a high-speed rail subgrade. The method comprises the following steps: respectively screening gravels in different particle diameters by virtue of sieve pores; determining the mixing amount of second-grade aggregates according to the change rule of a CBR value by taking the gravels with the particle diameter of 16 as first-grade aggregates and the gravels with the particle diameter of 19 as the second-grade aggregates; adding third-grade aggregates into the optimally-proportioned mixed aggregates of the first-grade aggregates and the second-grade aggregates by taking the gravels with the particle diameter of 26.5 as the third-grade aggregates, and determining the mixing amount of the third-grade aggregates by measuring the change rule of the CBR value; respectively determining the optimal mixing amount of fourth-grade gravel aggregates with the particle diameter of 13.2, fifth-grade gravel aggregates with the particle diameter of 9.5 and sixth-grade gravel aggregates with the particle diameter of 4.75 by adopting the same method; finally determining the mixing amount of the gravels with the different particle diameters in the coarse aggregates; determining the grading of fine aggregates according to a theoretical calculation method based on a K value; mixing the theoretically-calculated fine aggregates with the coarse aggregates, and carrying out a CBR test on the mixed aggregates so as to determine the grading of the coarse aggregates and the fine aggregates. The method can be used for efficiently, visually and accurately reflecting the basic performance of the graded gravels taken as the subgrade so as to provide a necessary guarantee for construction quality and engineering safety.