Abstract: To improve the quality efficiency, and promote green and low-carbon practices in subgrade compaction, a series of field tests are conducted on a large thickness of coarse-grained subgrade (80 cm) at variable frequencies, resonance frequencies, and conventional compaction methods (30 cm). The phenomenon that the subgrade soil was compacted under different vibration frequencies were revealed. The compaction characteristics of the large thickness of coarse-grained subgrade, as well as the evolution of mechanical parameters, were elucidated. Additionally, the fuel consumption and economic benefits of the compaction of the large thickness subgrade were analyzed. A high-energy, low-carbon compaction technique for large thickness subgrade based on resonance frequency was proposed. Results show that the coarse-grained subgrade exhibites resonance at frequencies between 20 to 25 Hz, with an increase in the vibration amplitude of the roller by 18% to 30%. After one static compaction, followed by five high-energy resonance compactions, and then additional static compaction, the degree of compaction of the thick subgrade reaches 95.36%, 95.41%, and 94.13% for the upper, middle, and lower layers, respectively, remaining homogenous along the depth. The degree of compaction, deflection, dynamic deformation modulus, and foundation deformation coefficient all met design and specification requirements. Compared to conventional compaction, the high-energy resonance compaction reduces carbon dioxide emissions and construction costs by 42% and 39%, respectively. The construction efficiency increases by 46% for the large thickness subgrade.