Research on Carbon Emission Characteristics and Reduction Potentials of Tunnel Construction
In order to clarify the carbon emission intensity and contribution of tunnel construction and guide the low-carbon transformation of tunnel construction,the carbon emission characteristics of highway tunnels and carbon reduction potential under different scenarios were quantitatively analyzed based on the life cycle assessment and emission factor method.The results shown that the average carbon emission intensity of highway tunnel construction was 34.370 tCO2eq/km,the contribution rates of carbon emission of material production,site construction machinery and site material transportation were 88.6％,9.2％and 2.2％respectively.Carbon emission sources are mainly concentrated in a few materials and machinery.Among which cement,steel bars,cold-rolled ribbed steel mesh,air compressors,dump trucks,axial fans and loaders need to be focused on.Also,the carbon emission intensity of tunnel excavation,tunnel lining,invert arch and pavement in tunnel were relatively high and needs to be focused on low-carbon optimization both design and construction.The carbon emission intensity of invert arch and tunnel excavation is positively correlated with the length of grade-Ⅳ and grade-V surrounding rock.Scenario analysis shown that the low-carbon replacement of cement can reduce the carbon emissions of material production by 1.83％to 10.92％,the low-carbon replacement of steel can reduce the carbon emissions of material production by 0.75％to 5.99％,and the replacement of electric construction machinery can reduce the carbon emissions of on-site transportation by 3.48％to 17.40％and the carbon emissions of on-site construction machinery by 0.5％to 2.53％.
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