Comparative Analysis of Carbon Emissions from Filled Embankment and Excavated Graben Schemes of Railway Subgrade Engineering

To quantitatively compare the carbon emissions between the filled embankment scheme and the excavated graben scheme of railway subgrade engineering, first, according to the life cycle assessment theory, the two schemes were separated into four stages: building materials production, building materials transportation, construction, and operation and maintenance. The carbon emission factor method was then used to compute the carbon emissions of the filled embankment scheme and the excavated graben scheme. The results indicate that the carbon emissions of the filled embankment scheme are 8783.76 t, 801.71 t, 627.78 t, and 1021.33 t at each stage, and 11,234.58 t over its total life cycle. The carbon emissions at each stage of the excavated graben scheme are 954.96 t, 52.62 t, 772.69 t, and 178.03 t, respectively, and 1958.30 t over its total life cycle. Finally, the carbon abatement potential of the excavated graben scheme with less carbon emissions was investigated by changing the soil nail wall slope to an ecological slope. The results show that after changing the soil nail wall slope of the excavated graben scheme to an ecological slope, the excavated graben scheme’s carbon sequestration of the total life cycle is 3274.38 t.