公路工程

为明晰隧道建设碳排放强度及贡献，指导隧道建设低碳转型，基于生命周期评价理论和排放因子法对公路隧道碳排放特征及不同情景下减碳潜力进行量化分析。研究结果表明：公路隧道建设碳排放强度平均值为3.437万t CO_2eq/km,材料生产、现场施工机械及场内材料转运碳排放贡献率分别为88.6%、9.2%和2.2%。碳排放来源主要集中于少数材料和机械，其中水泥、钢筋、冷轧带肋钢筋网、空气压缩机、自卸汽车、轴流式通风机、装载机需要进行重点管控。洞身开挖、洞身衬砌、仰拱、洞内路面碳排放强度较高需重点开展设计施工低碳优化，仰拱、洞身开挖碳排放强度与IV、V级围岩长度呈显著正相关。情景分析得到水泥低碳替代可减少1.83%～10.92%的材料生产碳排放，钢铁低碳替代可减少0.75%～5.99%的材料生产碳排放，电动化工程机械替代可减少3.48%～17.40%的场内运输碳排放和0.5%～2.53%的现场施工机械碳排放。

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 t CO_2eq/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%.